Ex Libris
C. K. OGDEN
O F T H E
I, AW S of C H A N C E,
M E T* H O D
Of Calculation of the
Hazards of GAME,
Plainly demonftrated,
And applied to GAMES at prefent
inoft in Ufe ;
Which may be eafily extended to the mofl
intricate Cafes of CHANCE imaginable.
The FOURTH EDITION,
Revis'd by JOHN HAM.
By whom is added,
A Demonftration of the Gain of the Banker in any
Circumftance of the Game call'd PH ARAON ;
And how to determine the Odds at the
ACE of HEARTS or FAIR CHANCE ;
With the Arithmetical Solution of fome
Queftions relating to LOTTERIES;
And a few Remarks upon HAZARD and
BACKGAMMON.
LONDON:
Printed for B. MOTTE and C. BAT HURST, at the
Middle- temple Gate in Fket-Jireet. M.DC c .xxx v 1 1 1 .
'
[ail
PREFACE.
T is thought as neceffary to write
a Preface before a Book, as it
is judgd civ//, when you invite
a Friend to Dinner, to proffer
him a Glafs of Hock beforehand for a
Whet : And this being maim'd enough
for want of a 'Dedication, I am refolv 'd
it fball not want an Epiflle to the
Reader too. I fhall not take upon me to
determine, whether it is lawful to play
at *Dice or not, leaving that to be dtf-
puted betwixt the Fanatick Parfons and
the Sharpers ; / am fure it is lawful to
deal with 'Dice as with other Epidemic
*Diflemprs ; and I am confident that the
writing a Book about it, will contribute ai
little towards its Encouragement, 'as Flux-
ing and 'Precipitates do to Whoring.
A 3, It
iv PR EF ACE.
It will be to little purpofe to tell my
Reader, of how great Antiquity the play-
ing at T)tce is. I will only let him know-,
that by the Alcae Lucius, the Antients com-
prehended all Games, which were fubjec-
ted to the determination of mere Chance ;
this fort of Gaming was fir iff ly forbid by
the Emperor Juftinian, Cod. Lib. 3. Tit.
43. under very fey ere Penalties', and Pho-
cius Nomocan. Tit. 9. Cap. 27. acquaints
us, that the Ufe of this was altogether
denied the Clergy of that time. Seneca
fays very well, Aleator quanto in arte eft
melior, tamo eft nequior ; That by how
much the one is more skilful in Games, by
fo much he is the more culpable; or we
may fay of this, as an ingenious Man fays
of T)ancingi That to be extraordinary good
at it, is to be excellant in a Fault ; there-
fore I hope no body will imagine I had fo
mean a ^ejign in this, as to teach the Art
of T laying at
A great part of this ^Difconrfe is a
Tranflation from Monf. Huygen'j Treatife,
De ratiociniis in ludo Alcse ; one, who in
his Improvements of 'Philofophy, has but
one Superior, and I think few or no K-
quals. The whole I undertook for my own
tDivertifement, next to the Satisfaction of
foms
P R E F A C.^E. V
fome Friends, who would now and then
be wrangling about the ^Proportions of
Hazards in fome Cafes that are here de-
cided. All it requir'd was a few fpare
Hours, and but little Work for the Brain ;
my T>efign in publishing it, was to make
it of more general Ufe, and perhaps per-
fuade a raw Squire, by it, to keep his Mo-
ney in his ^Pocket -, and if, upon this ac-
count, I fhould incur the Clamours of the
Sharpers, I do not much regard it, Jince
they are a fort of ^People the World is not
bound to provide for.
Ton willfnd here a very plain and eafy
Method of the Calculation of the Hazards
of Game, which a man may under ft and,with~
out knowing the Quadratures of Curves,
the "Doctrine of Series's, or the Laws
of Conccntripetation of Bodies, or the
^Periods of the Satellites of Jupiter ; yea,
without fa much as the Elements ^Eu-
clid. There is nothing required for the
comprehending the whole, but common Senfe
ana practical Arithmetick ; facing a few
Touches of Algebra, as in the frft Three
'Proportions, where the Reader, without
fufpicion of *Popery^ may make ufe of a
ftrong implicit Faith ; tho I muft confefs^
it docs not much recommend it fclf to me
in thefe Turpofes ; for / had rather he
would
vi PREFACE.
would enquire, and I believe he will frid
the Speculation not tinpleafant.
Every mans Succefs m any Affair is
proportional to his Conduct and Fortune.
Fortune (in the fenfe of moft f People}Jig-
wfies an Event which depends on Chance^
agreeing with my Wi$\ and Misfor-
tune fignifies fuch an one, whofe imme-
diate Caufes 1 don't know, and consequently
can neither for et el nor produce it (for it is
no Here/} to believe^ that Providence Buf-
fers ordinary matters to run in the Chan-
nel of fecond Caufes}. Now I fuppofe,
that all a wife Man can do in fuch a Cafe
ts y to lay his Buftnefs on fuch Events, as
have the moft powerful fecond Caufes, and
this is true both in the great Events of
the World, and in ordinary Games. It
is impojfible for a , with fuch deter-
mirid force and direction, not to fall on
fuch a determined fide, only 1 don't know
the force and direction which makes it
fall on fuch a detennirid Jide, and there-
fore I call that Chance, which is no-
thing but want of Art -, that only which
is left to me, is to wager where there
are the greateft number of Chances^ and
confidently the greateft probability to
gain -, and the whole Art of Gaming,
where there is any thing of Hazard, will
be
PREFACE. vii
fie r edited to this at lafl, viz, in dubious
Cafes to calculate on which fide there are
moft Chances j and tho' this can't bt done
in the mid ft of Game precifely to an Unitj
yet a Man who knows the 'Principles ', may
make fitch a conjecture, as will be a fuf-
fcient direction to him ; and tho' it is pof-
fible, if there are any Chances againft him
at all, that he may loft, yet when he chufith
the fafeft fide> he may fart with his Mo-
ney with more content (if there can be any
at all] in fitch a Cafe.
. I will not debate, whether one may en-
gge another in a disadvantageous Wager.
Games may be fupposd to be a try at of
Wit as well as Fortune, and every Man,
when he enttrs the Lifts with another^
unlefs out of Complaifance, takes it for
granted^ his Fortune and Judgment, are,
at Icaft, equal to thofe of his *P lay -Fellow;
but this I am fure of, that falfe Dice,
Tricks of Lcger-dc-main, &c. are inex-
cufable, for the queftion in Gaming is not y
Who is the heft Jnglcr ?
The Reader may here obferve the Force
of Numbers, which can be fuccefsfully ap-
plied, even to thofe things, which one
would imagine are fubjett to no Rules.
There are very few things which we know y
which
viii PREFACE.
which are not capable of being reduced to a
Mathematical Reafonmg-, and when they
cannot , it's a fign our Knowledge of them
is very fmall and confus'd 5 and where a
mathematical reasoning can be had, it's as
great folly to make life of any other, as to
grope for a thing in the dark y when you
have a Candle flanding by you. I Relieve
the Calculation of the Quantity of 'Pro-
bability might be improved to a very ufe-
ful and pie af ant Speculation, and applied
to a great many Events which are acci-
dental, befides thofe of Games ; only thefe
Cafes would be infinitely more confused, as
depending on Chances which the mo ft part
of Men are ignorant of-, and as 1 have
hinted already, all the Politicks in the
JVorld, are nothing elfe but a kind of Ana-
lyfis of the Quantity of probability in
cafual Events, and a good 'Politician (ig-
Tiifies no more? but one who is dextrous at
fuchCalculations ; only theTrinciples which
are madeufe of in the Solution of Juch J'ro-
blems^ cant be ftudied in a Clofet, but ac-
quir'd by the Obfcrvatien of Mankind.
There is likewife a Calculation of the
Quantity of 'Probability founded on Ex-
perience, to be made ttfe of in JVagers a-
bout any thing ; it is odds> if a Woman is
with
PREFACE. be
with Child, but it fhall be a Boy 5 and if
you would know the juft odds, you muft
confider the 'Proportion in the Bills that
the Males bear to the Females : The Tearly
Bills of Mortality are obfer c u t d to bear fuch
^Proportion to the live People as i to 30,
or 26 ; therefore it is an even Wager y
that one out of thirteen, dies within a
Tear (which may be a good reafon, tho
not the true, of that foolifi piece of Super-
Jlitiori], becaufe, at this rate, if i out of
2.6 dies, you are no lofer. It is but i to
18 if you meet a Parfon in the Street ,
that he proves to be a Non-Juror, becaufe
there is but i of $6 that are fuch. It is
hardly i to 10, that a Woman of Twenty
Tears old has her Maidenhead, and almoft
the fame Wager, that a Town -Spark of
that Age has not been clap'd. / think a
Man might venture fome odds, that 100
of the Gens d'arms beats an equal Number
of Dutch Troopers; and that an Englifh
Regiment ftands its ground as long as ano-
ther, making Experience our Guide in all
thefe Cafes and others of the like nature.
But there are no cafual Events, which
are fo eafily fubjeffed to Numbers, as thoft
of Games ; and I believe, there the Specu-
lation might be improved fo far, as to bring
in the Doctrine of the Series'.? and Loga-
a rithms.
x PREFACE.
richms. Since Gaming is become a Trade,
1 think it ft the Adventurers fiould be
upon the Square ; and therefore in the Con-
trivance of Games there ought to be aftrift
Calculation made ufe of] that they mayn't
put one Tarty in more probability to gain
than another ; and likewife, if a Man has
a conjtderable Venture ; he ought to be al-
low d to withdraw his Money when he
pleafes, paying according to the Circum-
Jtances he is then in : and it were eafy in
moft Games to make Tables, by Infpeffion
of which, a Man might know what he
was either to pay or receive, in any Cir-
cumjlances you can imagin-, it being conve*
Silent to fave apart of ones Money, rather
than venture the lofs of it all.
I fa-all add no more, but that a Ma-
. thematician will eajily perceive, it is not
.put in fuc h a Drefs as to be taken notice
oj by him, there being abundance of Words
fpent to make the more ordinary fort of
'People under jland it.
FOR the fake of thofe who are not
vers'd in Mathematicks, I have added
the following Explanation of Signs.
= Equal.
4- More, or to be added.
Lefs, or to be fubtra&ed.
x Multiplied.
-f- Divided.
EXAMPLE.'
3 x4-f- 3 i = i4 = |tf, is to be
read thus $
3 multiplied in 4, more by 3, lefs by i]
is equal to 14, which is equal to five
ninth parts of a.
An EXACT
METHOD
For S O LV I N G the
HAZARDS of G A M E.
LTHO' the Events of Games,
which Fortune folely governs, are
uncertain, yet it may be certainly
determin'd, how much one is
more ready to lofe than gain. "For Example:
If one mould wager, at the firft throw with
one Die, to throw fix, it's an accident if he
gains or not ; but by how much it's more
probable he will lofq than gain, is really de~
termin'd by the Nature of the thing, and
capable of a ftricl: Calculation. So likewife
if I mould play with another on tfyis con-
dition, that the Victory mould be to the
three nrft Games, and I had gain'd one al-
B ready,
2 Solution of the
ready, it is flill uncertain who mall gain
the third j yet by a demonftrative Reafon-
ing, I can eflimate both the Value of his
Expectation and mine, and confequently (if
we agree to leave the Game imperfect) deter-
mine how great a mare of the Stakes belong
to me, and how much to my Play-fellow ;
or if any were defirous to take my place,
at what rate I ought to fell it. Hence may
arife innumerable Queries among two, three,
or more Gameflers : and lince the Calcula-
tion of thefe things is a little out of the
common Road, and can be oft-times apply'd
to good purpofe, I fhall briefly here ihew
how it is to be done, and afterwards ex-
plain thofe things which belong properly to
the Dice.
In both Cafes I fhall make ufe of this
Principle, Ones Hazard or Expectation to
gain any thing, is worth fo much, as, if he
had it, he could pur chafe the like Hazard or
Expectation again in a jujl and equal Game.
For Example, if one, without my Know-
ledge, mould hide in one hand 7 Shillings,
and in his other 3 Shillings, and put it to
my choice which Hand I would take, I fay
this is as much worth to me, as if he mould
give me 5 Shillings ; becaufe, if I have 5
Shillings, I can purchafe as good a Chance
again, and that in a fair and juft Game.
PRO-
HAZARDS of Game. 3
PROPOSITION I.
If I expett a or b, either of which, with
equal probability ', may fall to me, then my
Expectation is worth *t- y that is, the
half Sum of a and b.
THAT I may not only demonflrate,
but likewife invefligate this Rule,
fuppofe the Value of my Expectation be x-,
by the former Principle having x, I can
purchafe as good an Expectation again in a
fair and juft Game. Suppofe then I play
with another on thefe terms, That every
one flakes x, and the Gainer give to the
Lofer a, this Game is juft ? and it appears,
that at this rate, I have an equal hazard
either to get a if I lofe the Game, or 2x^-a
if I gain ; for in this cafe I get 2X, which
are the Stakes, out of which I muft pay
the other a ; but if 2x a were worth k 9
then I have an equal hazard to get a or b ;
therefore making 2x ==^, #== 7-'
which is the Value of my Expectation.
The Demonstration is eafy ; for having
a ^ , I can play with another who will
flake ^~- againfl it, on this condition,
that the Gainer fhould give to the Lofer a;
B 2 by
4 Solution of tie
by this means I have an equal Expectation
to get a if I lofe, or b if I win ; for in the
laft cafe I get d-\-b the Stakes, out of
which I muft pay a to my Play-fellow.
In Numbers : if I had an equal hazard
to get 3 or 7, then by this Proportion,
my Expectation is worth 5, and it is cer-
tain, having 5, 1 may have the fame Chance ;
for if I play with another, fo that every
one flakes 5, and the Gainer pay to the
Lofer 3, this is a fair way of gaming j and
it is evident I have an equal hazard to get
3 if I lofe, or 7 if I gain.
PROP. II.
IJ I expett a, b, ore, either of which, 'with
equal facility ^ may happen ^ then the Value
of my Expectation is - H , or the,
third part of the Sum of& 3 b, and c.
FO R the Inveftigation of which, fup-
pofe x be the value of my Expecta-
tion j then x muft be fuch, as I can pur-
chafe with it the fame Expectation in a
jufl Game: Suppofe the Conditions of the
Game be, that playing with two others,
each of us flakes x, and I bargain with one
of the Gameflers, if I win, to give him b,
andrhe fhall do the fame to me 5 but with
the.
HAZARDS of Game. 5
the other, that if I gain, I (hall give him c >
and vice versa ; this is fair play : And here
I have an equal hazard to get b y if the firft
win, c if the fecond, or 3 AT c if I
gain myfelf ; for then I get 3*, viz. the
Stakes, of which I give the one b and the
other c ; but if 3* b c be equal to
a, I have an equal Expectation of a, b y
or c therefore making 3* b c = a,
t which is the Value of my
After the fame Method you
will find, if I had an equal hazard to get
a, b y c, or d, the Value of my Expectation
+ +c + tl y that is the fourth part of the
Sum of a, b t c, and d, &c.
PROP.
6 Solution of the
PROP. III.
y the number of Chances, by which a falls to
me, be p, and the number of Chances, by
which b falls, be q, and fuppofing all the
Chances do happen with equal facility, then
the Value of my Expectation is lii q 5 i. e .
the Product of a multiplied in the number
cf its Chances added to the Product of b,
multiplied into the number of its Chances,
end the Sum divided by the number of
Chances both of a and b.
SUppofe, as before, x be the Value of
my Expectation ; then if I have x, I
muft be able to purchafe with it that fame
Expectation again in a fair Game : For
this I mall take as many Play-fellows as,
with me, make up the number of p -f- q,
of which let every one flake x, fo the
whole Stake will be px 4- qx, and every
one plays with equal hopes of winning ;
with as many of my Fellow- Gamefters as
the Number q ftands for, I make this bar-
gain one by one, that whoever of them
gains #iall give me b, and if I win, I mall
do fo to them ; with every one of the reft
of the Gamefters, whofe Number is/> i,
I make this bargain, that whoever of them
gains,
HAZARDS of Game. 7
gains, (hall give me a, and I {hall give
every one of them as much, if I gain :
It's evident this is fair play ; for no Man
here is injur'd j and in this cafe I have
q Expectations to gain b y and p i Ex-
pectations to gain #, and i Expectation
(viz. when I win myfelf ) to get px -+- qx
bq a p -f- a ; for then I am to deliver
b to every one of the q Players, and a to
every one of the p i Gameflers, which
makes qb-\-pa a ; if therefore qx -f- bx
bq ap -+- a were equal to a, I would
have/> Expectations of a (fince juft now I had
p i Expectations of it) and ^Expecta-
tions of b, and fo would have juft come to
my nrft Expectation ; therefore putting
px-\-qx bq ap-\-a = a, then is x =
ap -4- bq
f +1
In Numbers : If I had 3 Chances to gain
for 13, and 2 for 8, by this Rule, my ha-
zard is worth ii; for 1 3 multiplied by 3
gives 39, and 8 by 2 1 6, thefe two added,
make 55, divided by 5 is iij and I can
eafily ihew, if I have n, I can come to
the like Expectation again ; for playing
with four others, and every one of us
flaking u, with two of them I make this
bargain, that whoever gains fhall give me
8, and I fhall too do fo to them ; with the
other two I make this bargain, that who-
ever
8 Solution of the
ever gains mall give me 13, and I them as
much if I gain : it appears, by this means
I have two Expectations to get 8, viz.
if any of the firft two gain, and 3 Expec-
tations to get 13, viz. if either I or any
of the other two gain ; for in this cafe I
gain the Stakes, which are 55, out of
which I am oblig'd to give the firft two 8,
and the other two 13, and fo there re-
mains 13 for myfelf.
PROP. IV.
fflat I may come to the Queftion proposed,
viz. 'The making a juft Diftribution a-
mongft Gamefters, 'when their Hazards
are unequal } ive muft begin with the moft
eafy Cafes.
SUppofe then I play with another, on
condition that he who wins the three
firit Games mall have the Stakes, and that
I have already gain'd two, I would know,
if we agree to break off the Game, and
part the Stakes juftly, how much falls to
my mare ?
The firft thing we muft confider in fuch
Queftions is the number of Games that
are wanting to both : For Example, if it
had been agreed betwixt us, that he mould
have the Stakes who gain'd the firft 20
Games,
HAZARDS of Game. Cy
Games, and if I had gain'd already 19,
and rny Fellow-Gamefler but 18, my ha-
zard is as much better than his in that cafe,
as in this propofed, viz. When of 3 Games
I have 2, and he but one, becaufe in both
cafes there's 2 wanting to him, and i to
me.
In the next place, to find the portion of
the Stakes due to each of us, we muft
confider what would happen if the Game
went on j it is certain, if I gain the firft
Game, I get the Stake, which I call a ,
but if he gain'd, both our Lots would be
equal, and fo there would fall to each of
us ~a -, but iince I have an equal hazard
to gain or lofe the firfl Game, I have an
equal Expectation to gain a, or a, which,
by the firft Propofition y is as much worth as
the half Sum of both, /. e. %a, fo there is
left to my Fellow-Gamefter a ; from
whence it follows, that he who would buy
my Game, ought to pay me for it %a > and
therefore, he who undertakes to gain one
Game before another gains two, may wager
3 to I '
PROP;
liO Solution of the
PHOP. V.
Suppofe Iivant but one Game, and my Fellow-*
Gamefier three, it is required to make a
juji ibijlribution of the Stake.
LE T us here likewife confider in what
ftate we mould be, if I or he gain'd
the firft Game j if I gain, I have the Stake
a, if he, then he wants yet 2 Games, and
I but i, and therefore we mould be in the
fame Condition which is fuppofed in the
former Proportion j and fo there would fall
to my Share, as was demonftrated there,
^a ; therefore with equal facility there may
happen to me a, or A^ which, by the firft
Proportion, is worth ^, and to my Fel-
low-Gamefter there is left -#, and there-
fore my hazard to his is as 7 to i.
As the Calculation of the former Propo-
fition was requifite for this, fo this will
ferve for the following. If I mould fup-
pofe myfelf to want but one Game, and
my Fellow four, (by the fame Method)
you will find -j-f of the Stake belongs to-
me, and -^ to him.
PROP.
HAZARDS of Game. \ t
PROP. VI.
Suppofe I want two Games, and my Fellow*
Gamejler three.
THEN by the next Game it will hap-
pen that I want but one, and he
three, which (by the preceding Proportion)
is worth ^a j or that we mould both want
two, whence there will be \a due to each
of us : now I being in an equal probability
to gain or lofe the next Game, I have an
equal hazard to 'gain ^a or \a, which by
the firft Proportion is worth ^a j and fo
there are eleven parts of the Stakes due to
me, and five to my Fellow.
PROP. VII.
Let us fuppoje I want two Games, and my
Fellow four.
IF I gain the next Game, then I mall
want but one, and my Fellow four -,
but if I lofe it, then I {hall want two, and
he three : So I have an equal hazard for
gaining ^-f a t or 4.^7, which, by the firfr,
is worth -iftf : So it. appears, that he who is
to gain two Games ior the other's four, i
in a better condition than he who is to.
C 2
t % Solution of tie
gain one for the other's two ; for my {hare
in the firfl cafe is ^a or LLa y which is lefs
than ~L ) my mare in the laft.
PROP. VIII.
Let us fuppofe three Gamefters, whereof the
Jirji and fecond 'want i Game, but the
third 2.
TO find the mare of the fir ft, we muft
confider what would happen if ei-
ther he, or any of the other two gain'd the
firft Game j if he gains, then he has the
Stake a ; if the fecond gain, he has nothing;
but if the third gain, then each of them
would want a Game, and fo La would be
due to every one of them. Thus the firft
Gamefter has one Expectation to gain a y
one to gain nothing, and one for La, (fince
all are in equal probability to gain the firft
Game) which by the fecond Propofition is
worth a : Now fince the fecond Gamefter's
Condition is as good, his Share is like wife
%a, and fo there remains to the third ^a,
whofe Share might have been as eafily found
by itfelf.
HAZARDS of Game, 13
PROP. IX.
In any number of Gamefters you pleafe, a-
mongft whom there are fome who want,
more, fome fewer Games : To find what
is any one's Jhare in the Stake, we muft
conjider what would be due to him, whofe
Share we inveftigate, if either he, or any
of his Fellow-GameJiers fiould gam the
next following Game j add all their Shares
together, and divide the Sum by the num-
ber of the Gamejlers, the Quotient is his
Share you were feeking.
SUppofe three Gamefters A, B, and C ;
A wants i Game, B 2, and Clikewife
2, I would find what is the fliare of the
Stake due to B, which I {hall call q.
Firft, we muft confider what would fall
to B's Share, if either he, A, or C, wins
the next Game ; if A wins, the Game is
ended, fo he gets nothing ; if B himfelf
gain, then he wants i Game, A i, and
C 2 ; therefore, by the former Proportion,
there is due to him in that cafe %q, then
if C gains the next play, then A and C
would want but i, and -B 2; and there-
rfore, by the eighth Propofition, his Share
would be worth ^q ; add together what is
due to B in all thefe three Cafes, viz. o|f ,
14- Solution of the
^.q, the Sum is |^, which being divided
by 3, the number of Gamefters, gives ^q,
which is the Share of B fought for : The
Demonftration of this is clear from the
fecond Propofition, becaufe B has an equal
hazard to gain c$q or L^ that is "*rfo"H y >
i. e. -f\q : now it's evident the Divifor 3 is
the number of the Gamefters.
To find what is due to one in any cafe j
viz. if either he, or any of his Fellow-
Gamefters win the following Game ; we
rnuft confider firft the more fimple Cafes,
and by their help the following j for as
this Cafe could not be folv'd before the
Cafe of the eighth Propofition was calcu-
lated, in which, the Games wanting were
i, i, 2 ; fo the Cafe, where the Games
wanting are i, 2, 3, cannot be calculated,
without the Calculation of the Cafe, where
the Games wanting are i, 2, 2, (which we
have juft now perform'd) and likewife of
the Cafe, where the Games wanting are
i, i, 3, which can be done by the eighth:
And by this means you may reckon all the
Cafes comprehended in the following Tables,
and an infinite number of others.
Games
HAZARDS of Game.
Games wanting
Their Shares
Games wanting
Shares
i,l,Z\ 1,2,2,
4,4,1
',3,
3,n.i.liQ,6,3,
*7
a 7
, 40,1 1 121, 1 21,1 li 78,158,7 1 j;42, 179,
243
729
Games wanting 1,3,3} i, 3, 4
Their Shares |6 ; , 8, 81616,82,31
629,87,13
729
729
Games wanting
Their Shares
Games wanting
Their Shares
729
729
2. 1, 3
2, 3, 4
2, 3 f
'33, 55,^5
4>,i95> 8 3
433,635, 1 19
243
729
1187
As for the Dice; thefe Queftions may
be propofed, at how many Throws one
may wager to throw 6, or any Number
below that, with one Die j How many
Throws are required for 1 2 upon two Dice ;
or 1 8 on 3 j and feveral other Queftions to
this purpofe.
For the refolving of which, it muft be
confider'd, that in one Die there are fix
different Throws, all equally probable to
come up ; for I fuppofe the Die has the
exaft
1 6 Solution of tie
exact figure of a Cube : On two Dice
there are 36 different throws ; for in re^
fpedt to every throw of one Die, any one
throw of the 6 of the other Die may come
up; and 6 times 6 make 36. In three
Dice there are 216 different throws; for
iii relation to any of the 36 throws of
two Dice, any one of the fix of the third
may come up; and 6 times 36 make 216:
So in four Dice there are 6 times 216
throws, that is, 1296 : And fo forward
you may reckon the throws of any num-
ber of Dice, taking always, for the Addi-
tion of a new Die, 6 times the number of
the preceding.
Befides, it mufl be obferv'd, that in two
Dicfe there is only one way 2 or 12 can
come up ; two ways that 3 or 1 1 can come
up ; for if I fhall call the Dice A and B, to
make 3 there may be i in A, and 2 in B,
or 2 in A, and i in B ; fo to make 1 1,
there may be 5 in A, and 6 in B, or 6 in A,
and 5 in B ; for 4 there are three Chances,
3 in A, and i in B, 3 in B, and i in A,
or 2 as well in A as B ; for i o there are
'Jikewife three Chances ; for 5 or 9 there
are four Chances ; for 6 or 8 five Chances ;
for 7 there are fix Chances.
I In
HAZARDS of Game. 17
' 3 or 18
i
4 or 17
5 or 1 6
6 or 15
3
6
10
7 or 14
8 or 13
'5
21
9 or 12
2 5
. 10 or ii
2 7
In 3 Dice there are found
for
PROP. X.
To find at how many times one may under-^
take to throw 6 with one Die.
IF any mould undertake to throw 6 the
firft time, it's eviden Where's one Chance
gives him the Stake, and five which give
him nothing; for there are 5 throws a-
gainft him, and only one for him. Let
the Stake be call'd a, then he has one Ex-
pectation to gain #, and five to gain no-
thing, which, by the third Proportion, is
worth 0, and there remains for the other
tf j fo he who undertakes, with one Dif,
to throw 6 the firft time, ought to wager
only i to 5.
2. Suppofe one undertake, at two Throws
of i Die, to throw 6, his Hazard is cal-
culated thus ; if he throw 6 at the firft,
he has a the Stake ; if he do not, there re-
mains
1 8 Solution of the
mains to him one throw, which, by the
former Cafe, is worth ^a ; but there is but
one Chance which gives him 6 at the firft
throw, and five Chances againft him; fo
there is one Chance which gives him a>
and five which give him .*, which by the
fecond Pro^ofition, is worth J^a, fo there
remains to his Fellow-Gamefter * -, fo the
Value df my Expectation to his, is as n to
25, /. . lefs than i to 2.
By the fame method of Calculation, you
will find, that his hazard who undertakes
to throw 6 at three times with one Die,
is T 9 T V tf *~ tnat he can only lay 9 1 a-
gainft 125, which is fomething lefs than 3
to 4.
He who undertakes to do it at four times,
his hazard is T VyV^ f he may wager 67 r
againft 625, that is, fomething more than
1 to i.
He who undertakes to do it at five times,
his hazard is yff j-0, fo he can wager 4651
againft 3125, that is, fomething lefs than
3 to . 2 -
His hazard who undertakes to do it at 6
times, is ^-f-r tf > an ^ ^ e can wa g er 3 IO 3 r
againft 15625, that is, fomething leis than
2 to i.
Thus any number of throws may be eafily
found ; but the following Propoiition will
fhew you a more compendious way of Cal-
culation, PROP.
HAZARDS of Gam& 1 9
PROP. XT.
To Jlnd at hoiu many times one may undertake
to thrt/iv 1 2 with two Dice.
IF one fhould undertake it at one throw,
it's clear he has but one Chance to get
the Stake a, and 35 to get nothing ; which,
by the third Proportion, is worth ~ r a.
He who undertakes to do it at twice, if he
throw 1 2 the firft time, gains a j if otherwife,
then there remains to him one throw,
which, by the former Cafe, is worth ~^a ;
but there is but one Chance which gives 12
at the firft throw, and 35 Chances again ft
him j fo he has i Chance for a, and 35 for
Ts- a > which by the third Proportion is
worth T-J-JT^J and there remains to his
Fellow-Gamefter 44^.
From thefe it's eafy to find the Value of
his hazard, who undertakes it at four times,
palling by his cafe who undertakes it at
three times.
If he who undertakes to do it at four
times throws 12 the firfl or fecond Caft,
then he has a -, if not, there remains two
other throws, which, by the former Cafe,
are worth T ^ T a $ but for the fame reafon,
in his two firit throws, he has 7 1 Chances
which give him a, againft 1225 Chances,
D 2 i*
20 Solution of the
in which it may happen otherwife j there-
fore at firft he has 71 Chances which give
him a, and 1225 which give him -r^-J-ytf,
which by the third Proportion is worth,
^JLy.. 1 ^ which mews that their hazards
to one another are as 178991 to 1500625.
From which Cafes it is eafy to find the
Value of his Expe&ation, who undertakes
to do it at 8 times, and from that, his Cafe
who undertakes to do it at 1 6 times ; and
from his Cafe who undertakes to do it at 8
times, and his likewife who undertakes to
do it at 1 6 times ; it is eafy to determine
his Expectation who undertakes it at 24
times: In which Operation, becaufe that
which is principally fought, is the number
of throws, which makes the hazard 'equal
on both fides, viz. to him jyvho under-
takes, and he who offers, you may with-
out any fenfible Error, from the Numbers
(which elfe would grow very great) cut off
fome of the laft Figures. And fo I find,
that he who undertakes to throw 12 with
two Dice, at 24 times, has fome lofs ; and
he who undertakes it at 25 times, has fome
advantage.
PROP*
HAZARDS of Game. 2t
PROP. XII.
tfojind with how many Dice one can under*,
take to throw two Sixes at the firft Caft.
THIS is as much, as if one would
know, at how many throws of one
Die, he may undertake to throw twice
fix : now if any fhould undertake it, at
two throws, by what we have fhewn be-
fore,, his hazard would be T V*j he who
would undertake to do it at 3 times, if his
firft throw were not 6, then there would
remain two throws, each of which muft
be 6, which (as we have {aid) is worth ^a ;
but if the firft throw be 6, he wants only
one 6 in the two following throws, which
by the tenth Propofition, is worth 0-^a :
but fince he has but one Chance to get 6
the firft throw, and five to mifs it ; he has
therefore, at firft, one Chance for ^a, and
five Chances-for - l ^a, which, by the third
Propofition, is worth T VV*> or -sr a > a ^ ter
this manner ftill afluming i Chance more,
you will find that you may undertake to
throw two Sixes at 10 throws of one Die,
or i throw of ten Dice, and that with fome
advantage.
PROP.
Solution of the
PROP. XIII.
Jflam to play with another one Throw, on
this condition, that if j comes up I gain,
if 10 he gains ; if it happens that we muft
divide the Stake, and not play, to find
how much belongs to me, and how much
to him.
BEcaufe of the 36 different Throws of
the two Dice, there are fix which
give 7, and 3 which give 10, and 27 which
equals the Game, in which cafe there is
due to each of us \a : But if none of the
27 fhould happen, I have 6, by which I
may gain a, and 3, by which I may get
nothing, which by the third Proportion,
is worth ^a ; fo I have 27 Chances for a,
and 9 for ^a, which, by the third Propo-
iition, is worth ~^a, and there remains to
my Fellow-Gameiler ~^a.
PROP,
HAZARDS of Game. 23
PROP. XIV.
If I were playing with another by turns, with
two Dice, on this condition^ that if I throw
7 I gain, and if he throw 6 be gains, al-
lowing him the firjl throw : To find the pro-
portion of my Hazard to his.
SUppofe I call the Value of my Hazard
x, and the Stakes a, then his Hazard
will be a x ; then whenever it's his turn
to throw, my Hazard is x, but when it*s
mine, the Value of my Hazard is greater.
Suppofe I then call it y ; now becaufe of
the 36 throws of two Dice, there are five
which give my Fellow-Gamefter 6, thirty-
one which bring it again to my turn to
throw, I have five Chances for nothing,
and thirty-one for y, which, by the third
Propofition, is worth A^-y j but I fuppos'd
at firft my Hazard to be x ; therefore
|y s= x, and confequently y = .|4*- I
fuppos'd likewife, when it was my turn
to throw, the Value of my Hazard was y ;
but then I have fix Chances which give
me 7, and confequently the Stake, and
thirty which give my Fellow the Dice,
that is, make my Hazard worth x ; fo I
have fix Chances for a, and thirty for x,
which,
24 Solution of the
which, by Propofit. 3. is worth
but this by fuppofition is equal to y, which
is equal (by what has been prov'd already)
to-g*, therefore 2^ == **, and
confequently x = ^^a y the Value of my
Hazard, and that of my Fellow-Gamefter
is J4#, fo that mine is to his as 3 1 to 30.
Here follow feme ^uejiions which ferve to
exercije the former Rules.
1. A and B play together with two Dice,
A wins if he throws 6, and B if he throws
7 ; A at firft gets one throw, then B two,
then A two, and fo on by turns, till one
of them wins. I require the proportion of
A s Hazard to B's ? Anfwer, It is as 1 03 55
to 12276.
2. Three Gamefters, A, B, and C, take
12 Counters, of which there are four white
and eight black ; the Law of the Game is
this, that he fhall win, who, hood-wink'd,
(hall firft chufe a white Counter ; and that
A fhall have the firft choice, B the fecond,
and C the third, and fo, by turns, till one
of them win. Quar. What is the propor-
tion of their Hazards ?
HAZARDS of Game. 2$
3. ^wagers with B, that of 40 Cards,
that is, 10 of every Suit, he will pick out
four, fo that there (hall be one of every
fuit. A's Hazard to B's in this cafe is as
1000 to 8139.
4. Suppofing, as before, 4 white Coun-
ters and 8 black, A wagers with B, that
out of them he (hall pick 7 Counters, of
which there are. 3 white. I require the
proportion of A's Hazard to J5's ?
5. A and B taking 12 Counters, each
play with three Dice after this manner, that
if 1 1 comes up, A (hall give one Counter
to By but if 14 comes up, B mail give one
to A^ and that he lhall gain who firft has
all the Counters. A's Hazard to jB's is
244140625 to 282429536481.
The Calculus of the preceding Problems
is left out by Monf. Huygens, on purpofe
that the ingenious Reader may have the
fatisfa&ion of applying the former Method
himfelf ; it is in moft of them more labo-
rious than difficult : for Example, I have
pitch'd upon the fecond and third, be-
caufe the reft can be folv'd after the fame
Method.
6 PROBLEM
26 Sdut'wn of tb&
PROBLEM i.
The firft Problem is folv'd by the Me-
thod of Prop. 14. only with this difference,
that after you have found the Share due to
B 3 if A were to get no firft throw, you
muft fubtracl from it T s r of the Stake which
is due to A for his Hazard of throwing fix
at the Jfirft throw.
PROBLEM 2.
As for the fecond Problem, it is folv'd
thus 5 Suppofe jfs Hazard, when it is his
own turn to chufe, be x y when it is 5's, be
j, and when it is C*s, be z -, it is evident,
when out of 1 2 Counters, of which there
are 4 white and 8 black, he endeavours to
chufe a white one, he has four Chances
to get it, and eight to mifs it ; that is, he
has four Chances to get the Stake a, and
eight to make his hazard worthy : fox =2
^> , and confequently y = 1 2L=^ -
When it is B's turn to chufe, then he has
four Chances for nothing, and eight for
'z, (that is, to bring it to C's turn) confe-
quently y = ^z = l~p 4 - ; this Equa-
reduc'd gives K= Q . x ~^ a . w hen it
comes
HAZARDS of Game. 27
comes to (7s turn to chute, then A has four
Chances for nothing, and eight for x, con-
fequently z=^x, therefore ^x
this equation reduc'd gives x =.^a y and
confequently there remains to B and C -l-Jtf,
which muft be fhar'd after the fame man-
ner, that is, fo that B have the firft choice,
C the next, and fo on, till one of them
gain $ the reafon is, becaufe it had been
juft in A to have demanded T ^. of the
Stake for not playing, and then the Se-
niority fell to J5 > now ? a > parted be-
twixt B and C', by the former Method,
gives T ^ to By and T 4 T to C j fo A^ B, and
C"s Hazards from the beginning were as
9* 6 > 4-
I have fuppos'd here the Senfe of the
Problem to- be, that when any one chus'd
a Counter, he did not diminim their num-
ber ; but if he mifs'd of a white one, put
it in again, and left an equal hazard to
him who had the following choice ; for if
it be otherwife fuppos'd, A's fhare will be
T y T) which is lefs than T ^..
Prob. 2. It is evident, that wagering to
pick out 4 Cards out of 40, fo that there
be one of every Suit, is no more than wa-
gering, out of 39 Cards to take 3 which
fhall be of three propofed Suits ; for it is
all one which Card you draw firft, all the
E a hazard
28 Solution of the
hazard being, whether put of the 3 9 re-
maining you take 3, of which none fhall be
of the Suit you firft drew : Suppofe then
you had gone right for three times, and
were to draw your laft Card, it is clear
that there are 27 Cards, (viz. of the Suits
you have drawn before) of which, if you
draw any you lofe, and 10, of which if
you draw any, you have the Stake a j fo
you have 10 Chances for a, and 27 for
nothing, which, by Prop. 3. is worth yftf.
Suppofe again you had gone right only for
two Draughts, then you have 18 Cards
(of the Suits you have drawn before) which
make you lofe, and 20, which put you
in the Cafe fuppos'd formerly, viz. where
you have but one Card to draw, which,
as we have already calculated, is worth
JL^-a $ fo you have 18 Chances for nothing,
and 20 for JL*.a, which, by Prop. 3. is
worth y|-|tf. "Suppofe again you have 3
Cards to draw, then you have 9 (of the
Suit you drew firft) which make you lofe,
and 30 which put ycu in the cafe fuppos'd
laft ; fo you have 9 Chances for nothing,
and 30 for f|Jrf, which by Propof. 3. is
worth -J T y_? T an ^ y ou leave to
your Fellow-Gamelter |4j|- a ; fo your ha-
zard is to his as 1000 to 8139.
It is eafy to apply this Method to the
Games that are in ufe amongft us : For
Example^
HAZARDS of Game. 29
, If A and 5, playing at Backgam-
mon, A had already gain'd one end of three,
and B none, and if A had the Dice in his
Hand for the laft throw of the fecond end,
all his Men but two upon the Ace Point
being already caft off: $u and leave the refl
to A.
Thus likewife, if you apply the former
Rule to the Royal-Oak Lottery, you will
find, that he who wagers that any Figure
fhall come up at the firfl throw, ought to
wager i againfl 31 ; that he who wagers
it
30 Solution of the
it fhall come up at one of two throws^,
ought to wager 63 againft 961 ,- that he
who wagers that a Figure (hall come up at
once in three times, ought to lay 125055
againft 923521, Gfr. it being only fome-
what tedious to calculate the reft. Where
you will find, that the equality will not
fall as fome imagine on 16 Throws, no
more than the equality of wagering at how
many Throws of one Die 6 mall come up,
falls on three 5 the contrary of which you
have feen already demonftrated : you will
find by calculation, that he has the Dif-
advantage, who wagers, that i of the 32
different Throws of the Royal-Oak Lottery
fhall come at once of 20 times, and that
he has fome advantage, who wagers on 22
times, fo the neareft to Equality is on 21
times. But it muft be remembred, that
I have fuppos'd in the former Calculation,
the Ball in the Royal-Oak Lottery -to be re-
gular, tho' it can never be exactly fo ; for
he, who has the fmalleft Skill in Geometry,
knows, that there can be no regular Body
of 32 fides ; and yet this can be of no Ad-
vantage to him who keeps it.
HAZARDS of Game. 31
To find the Value of the Throws of
Dice, as to the Quantity.
. :
O thing is more eafy, than by the
former Method to determine the Va-
lue of any number of Throws of any num-
ber of Dice i for in one throw of a Die^
I have an equal Chance for i, 2, 3, 4, 5, 6,
confequently my Hazard is worth their
Sum 21 divided by their Number 6, that
is Si"- Now if one throw of a Die be
worth 37, then two throws of a Die, or
one throw of. two Dice is worth 7, two
throws of two Dice, or one throw of
four Dice is worth 14, &c. The general
Rule being to multiply the Number of
Dice, the Number of Throws, and 3-;-
continually.
This is not to be underftood as if it were
an equal wager to throw 7, or above it,
with two Dice at one throw ; for he who
undertakes to do fo, has the Advantage by
21 againft 15. The meaning is only, if
I were to have a Guinea, a Shilling, or
any thing elfe, for every Point that I threw
with
3 i Sol? & ion of the
with two Dice at one throw, my Hazard
is worth 7 of thefe, becaufe he who gave
me 7- for it, would have an equal probabi-
lity of gaining or loling by it, the Chances
of the Throws above 7, being as many as
of thefe below it : So it is more than an
equal wager to throw 14 at leaft at two
Throws of two Dice, becaufe it is more
probable that 14 will come, than any one
number befides, and as probable that it
will be above it as below it -, but if one
were to buy this Hazard at the rate above-
mention'd, he ought juft to give 14 for it.
The equal wager in one Throw of two
Dice, is to throw 7 at leaft one time, and
8 at leaft another time, and fo per vices :
The reafon is, becaufe in the firft Cafe I
have 2 1 Chances againft 1 5, and in the fe*
cond 15 Chances againft 21.
HAZARDS of Game. 33
Of RAF F LING.
IN Raffling, the different Throws- and
their Chances are thefe ; Where it is
to be obferved, that of the 216 ,, r ,
j-rr -T.I r i T^- Throws. Chan.
different Throws of three Dice,
there are only 96 that give Dou-
blets, or two, at leaft, of a
3
4
6
\
9
10
18
I
J 7
3
16
6
15
4
H
9
i3
9
12
7
II
9
kind ; fo it is 4 to 5 that with
three Dice you mall throw Dou-
blets, and it is i to 35 that you
throw a Raffle, or all three of
a kind. It is evident likewife,
that it is an even wager to throw
1 1 or above it, becaufe there are as many
Chances for 1 1, and the Throws above it,
as for the Throws below it ; but tho' it be
an even wager to throw 1 1 at one Throw, it
is a difad vantage to wager to throw 22 at two
Throws, and far more to wager to throw
33 at three Throws ; and yet it is more
than an equal Wager that you mall throw
21 at two Throws in Raffling, becaufe it
is as probable that you will, as that you will
not throw n, a$ leaft, the firft time, an4
F mor
34- Solution of the
more than probable that you will throw 10,
at leaft, the fecond time.
For an inftance of the plainnefs of the
preceding Method, I will mew, how by
iimple Subtraction, the moft part of the
former Problems may be folv'd.
Suppofe A and B, playing together, each
of them flakes 32 Shillings, and that A
wants one Game of the number agreed on,
and B wants two ; to find the {hare of the
Stakes due to each of them. It's plain, if
A wins the next Game, he has the whole
64 Shillings j if B wins it, then their
Shares are equal ; therefore fays A to B,
If you will break off the Game, give me
32, which I am fore of, whether I win or
lofe the next Game ; and fince you will
not venture for the other 32, let us part
them equally, that is, give me 16, which,
with the former 32 make 48, leaving 16
to you.
Suppofe A wanted one Game, and B
three; if A wins the next Game, he has
the 64 Shillings; if B wins it, then they
are in the condition formerly fuppos'd, in
which cafe there is 48 due to A ; there-
fore fays A to B, give me the 48 which I
am fure of, whether I win or lofe the next
Game; and fince you will not hazard for
the other 16, let us part them equally, that
is, give me S } which, witfc the former 48,
HAZARDS of Gams. 35
make 56, leaving 8 to you ; and fo all the
other Cafes may be folv'd after the fame
manner.
Suppofe A wagers with B, that with
one Die he fhall throw 6 at one of three
Throws, and that each of them ftakes 108
Guineas ; to find what is the proportion of
their Hazards. Now there being in one
Throw of a Die but one Chance for 6, and
five Chances againft it, one Throw for 6
is worth 4. of the Stake ; therefore fays B
to A y of the 216 Guineas take a fixth part
for your fir ft Throw, that is, 363 for your
next Throw take a fixth part of the re-
maining 1 80, that is, 30 > and for your
third Throw, take a fixth part of the re-
maining 150, that is, 25, which in all
make 91, leaving to me 125; fo his ha-
zard who undertakes to throw 6 at one of
three Throws, is 91 to 125.
Suppofe A had undertaken to throw 6
with one Die at one Throw of four, and
that the whole Stake is 1296 ; fays A to B y
every Throw for 6 of one Die, is worth
the fixth part of what I throw for ; there-
fore for my firft Throw give me 2 16, which
is the fixth part of 1296, and there re-
mains 1080, I muft have the fixth part
of that, viz. 1 80, for my fecond Throw ;
and the fixth part of the remaining 900,
which is 1 50, for my third Throw j and
F 2 the
36 Solution of the
the fixth part of the laft remainder 750,
which is 1 2 5 for my fourth j all this addedt
together makes 671, and there remains to
you 625 j fo it is evident, that As Hazard,
in this Cafe, is to 5's 671 to 625.
Suppofe A is to win the Stakes (which
we fhall fuppofe to be 36) if he throws 7
at once of twice with two Dice, and B is
to have them if he does not j fays B to A y
the Chances which give 7 are 6 of the 36,
which is as much as i of 6 5 therefore for
your fiift Throw you mall have a fixth
part of the 36, which is 6 ; and for your
next Throw a fixth part of the remainder
30, which is 5 5 this in all makes n ; fo
you leave 25 to me j fo A's Hazard is to
J5's as n to 25.
It were cafy," at this rate, to calculate
the moft intricate Hazards, were it not that
Fractions will occur j which, if they be
more than 4, may be fuppos'd equal to an
Unit, without caufing any remarkable Er-
ror in great Numbers.
It will not be amifs, before I conclude,
to give you a Rule for finding in any num-
ber of Games the Value of the firft, becaufe
Huygens's Method, in that cafe, is fomething
tedious.
Suppofe A and B had agreed, that he
mould have the Stakes who did win the
x firft 9 "Games, and A had already won one
* of
HAZARDS of Game. 37
of the 9 ; I would know what mare of .B's
Money is due to A for the Advantage of*
this Game. To find this, take the firft
eight even Numbers 2, 4, 6, 8, 10, 12, 14,
j 6, and multiply them continually , that
is, the firft by the fecond, the product by
the third, GV. take the firft eight odd Num-
bers i, 3, 5, 7, 9, n, 13, 15, and do juft
fo by them, the produc~l of the even Num-
ber is the Denominator, and the produd: of
the odd Number the Numerator of a Frac-
tion, which exprefleth the quantity of B's
Money due to A upon the winning of the
firfl Game of 9 ; that is, if each ftak'd a
number of Guineas, or Shillings, 6?r. ex-
prefs'd by the produdt of the even Num-
bers, there would belong to A, of jB's
Money, the Number exprefs'd by the pro-
duct of the odd Numbers. For Example,
Suppofe A had gain'd one Game of 4, then
by this Rule, I take the three firfl even
Numbers, 2, 4, 6, and multiply them con-
tinually, which make 48, and the firft
three odd Numbers, i, 3, 5, and multiply
them continually, which make 1 5 ; fo there
belongs to A JLJ, of B's Money, that is, if
each ftak'd 48, there would belong to A>
befides his own, 1 5 of B's. Now by Huy-
gem's Method, if A wants but three Games
while B wants four, there is due to A -|4
of the Stake; by this Rule there is due
to
38 Solution of the
to A 4| of 's Money, which is ~| of the
Stake, which, with his own j. of the
Stake, makes |. or .11 of the Stake; and
fo in every Caie you will find Huygens's
Method, and this will give you the fame
Number : A Demonstration of it you may
tin a Letter of Monfieur Pajcal's to
Dnfieur Fermat ; though it be otherwife
exprefs'd there than here, yet the confe-
quence is eafily fupply'd. To prevent the
labour of Calculation, I have fubjoin'd the
following Table, which is calculated for two
Gameflers, as Monfieur Huygens's is fot
three.
If each of us flake 256 Guineas in
96
V o
3
-
6
5
4
Game
63
70
80
2 ift
Games
126
140
1 60
3 \ft
Games
Games
182
224
200
240
224
256
5 l ft
Games
248
256
6 iji
Games
256
192
256
2
128
I
256
2 5 6
The
HAZARDS of G$me. 3 9
The Ufe of the Table is plain ; for let
our Stakes be what they will, I can find
the portion due to me upon the winning
the firft, or the firft two Games, Gfr. of
2, 3,4, 5, 6. For Example , If each of us
had ftak'd 4 Guineas, and the number of
Games to be play'd were 3, of which I
had gain'd i, fay, As 256 is to 96, fo is 4
to a fourth.
256 : 96 :: 4 ; if.
'To find what is the Value of hh Hazard,
who undertakes, at the firft Throw, tQ caft
Doublets, in any given number of Dice.
In two Dice it is plain, to avoid Dou-
blets, every one of the fix different Throws
of the firft, can only be combin'd with
five of the fecond, becaufe one of the fix
is of the fame kind, and confequently
makes Doublets j for the fame reafon, the
thirty Throws of two Dice, which are
not Doublets, can only be combin'd with
four Throws of a third Dice, and three
Throws of a fourth Dicej fo generally
it is this Series,
6x5x4x3x2x1x0,
6x6x6x6x6x6x6,
The.
40 Solution of the
The fecond Series is the Sum of the
Chances, and the firfl the Number of
Chances againft him who undertakes to
throw Doublets, each Series to be conti-
nu'd fo many terms, as are the number -of
Dice. For Example, If one mould under-
take to throw Doublets at the firft Throw
of four Dice, his Adverfary's Hazard is
*** x n = , or \ , leaving to him
6x6x6x6 1296 1 8 *
44, fo he has x 3 to 5. In feven Dice, you
fee the Chances againft him are o, be-
caufe then there muft neceffarily be Dou-
blets.
HAZARDS of Game* 41
Of W H i s T.
If there be four playing at Whift, it is 15
to i that any two of them /ball not have the
four Honours, which I demonftrate thus.
SUppofe the four Gamefters be A, B, C,
D : \iA and B had, while the Cards are
a dealing, already got three Honours, and
Wanted only one, lince it is as probable
that C and D will have the next Honour,
as A and E ; if A and B had laid a Wager
to have it, there is due to them but | of
the Stake : If A and B wanted two of the
four, and had wager'd to have both thofe
two, then they have an equal hazard to get
nothing, if they mifs the firfl of thefe two,
or to put themfelves in the former Cafe
if they get j fo they have an equal Ha-
zard to get nothing, or -J, which, by
Prop. i. is worth * of the Stake ; fo if they
want three Honours, you will find due to
them 4- of the Stake j and if they wanted
four, -rr f ^ e Stake, leaving C and D
4^; foC and> can wager 15 to i, that
G A
42 Solution of the
A and B mall not have all the four Ho-
nours.
It is n to $ that A and B Jhall not have
three of the four Honours^ which I prove
thus :
It is an even Wager, if there were but
three Honours, that A and B mall have
two of thefe three, fince 'tis as probable
that they will have two of the three, as
that C and JD (hall have them ; confe-
quently, if A and B had laid a Wager to
have two of three, there is due to them 1
of the Stake. Now fuppofe A and B had
wager'd to have three of four, they have
an equal hazard to get the firft of the
four, or mifs it ; if they get it, then they
want two of the three, and confequently
there is due to them ! of the Stake j if
they mifs it, then they want three of the
three, and confequently there is due to
them f of the Stake j therefore, by Prop.
i. their Hazard is worth T s r , leaving to C
and D -K..
A and B playing at Whift againft G and D;
A and B have eight of ten, and C and T)
nine, and therefore can't reckon Honours j to
find the proportion of their Hazards.
There
HAZARDS of Game. 43
There is T s r due to A and B upon their
hazard of having three of four Honours >
but fince C and D want but one Game,
and A and $ two, there is due to A and
j5 but -y, or T ^ more upon that account,
by Prop. 4. this in all makes T 9 r , leaving to
C, and D T T T j fo the hazard of A and 5 to
that of C and Z), is as 9 to 7.
In the former Calculations I have ab-
ftra&ed from the fmail difference of having
the Deal, and being Seniors.
All the former Cafes can be calculated
by the Theorems laid down by Monfieur
Huygens $ but Cafes more compos'd re-
quire other Principles : for the eafy and
ready Computation of which, I mall add
pjie Theorem more, demonftrated after Mon-
fieur Huygens's Method.
TH EORE M.
If I have p Chances for a, q Chances
for b t and r Chances for c, then my hazard
is worth ap+ q ^ cr ; that is, a multiplied
/-t-?-H r
into the number of its Chances added to
b, multiplied into the number of its Chan-
ces, added to c, multiplied into the num-
ber of its Chances, and the Sum divided by
the Sum of Chances of a, b t c.
G 2 To
^4 Solution of the
To inveftigate as well ,as demonn;ra.te
this Theorem, fuppcfe the value of my ha-
zard be x, then x muft be fuch, as having
it, I am able to purchafe as good a hazard
again in a juft and equal Game. Suppofe
the Law of it be this, That playing with
fo many Gamefters as, with myfelf, make
up the number pj-q-\-r t with as many of
them as the number p reprefents, I make
this bargain, that whoever of them wins
mall give me a, and that I (hall do fo to
each of them if I win j with the Game-
fters reprefented by the number of q y I
bargain to get ^, if any of them win, and
tp give b to each of them, if I win my
felf j and with the reft of the Gamefters,
whofe number is r< i, I bargain to give,
or to get c after the fame manner ; Now
all being in an equal probability to gain, I
Jiave^ Chances to get a y q Chances to get
b, and r- i Chances to get r,-and one
Chance, viz. when I win myfelf, to get
fx -f- qx -+-rx ap bq re -h c , which,
if it be ibppos'd equal to c , then I have p
Chances for a, q Chances for b t and r
Chances for c (for I had juft now r i
Chances for it) and therefore, in cafe px -f-
qx -+- rx ap bq rc-i-c = c, then is
... */. 4- fy 4- t r
By
HAZARDS of Game. 45
By the fame way of reafoning ou will
find, If I have p Chances for , q Chances
for b, r Chances for c, and s Chances for
d, that my hazard is
In NUMBERS.
If I had two Chances for 3 Shillings,
four Chances for 5 Shillings, and one
Chance for 9 Shillings, then, by this Rule,
my hazard is worth 5 Shillings j for
_^ s to
prove, that with five Shillings I can pur-
chafe a like hazard again j for fuppofe I
play with fix others, each of us flaking
5 Shillings ; with two of them I bargain,
that if either of them win, he muft give
me 3 Shillings, and that I mail do fo to
them ; and with the other four I bargain
juft fo, to give or to get 5 Shillings :
This is a juft Game, and all being in an
equal probability to win 5 by this means
I have two Chances to get 3 Shillings,
four 'Chances to get 5 Shillings, and one
Chance to get 9 Shillings, viz. when I
win my felf ; for then out of the Stake,
which makes 35 Shillings, I muft give the.
firft two 6 Shillings, and the other four 20
Shillings, fo there remains juft 9 to myfelf.
46 Solution of the
It is eafy, by the help of this Theorem^
to calculate in the Game of Dice, com-
monly call'd Hazard, what Mains are beft
to fet on, and who has the Advantage,
the Carter or Setter. The Scheme of the
Game, as I take it, is thus }
Mains.
V.
VI.
VII.
VIII.
IX.
Throws next following for
-A.
The Coffer.
V.
VI. XII.
VII. XL
VIII. XII.
IX.
The Setter.
II. III. XL XII.
XL II. III.
XII. II. III.
XL II. III.
II. III. XL XII.
By an eafy Calculation you will find,
if the Carter has IV,. and the Setter VII,
there is due to the Carter JL of the Stake ;
if he has
V againrt VII, ^ of the Stake.
VI againft VII, T s - of the Stake.
IV againrt VI, 4 of the Stake.
V againft VI, *. of the Stake.
IV againft V, f of the Stake.
I need not tell the Reader, that IV is
the fame with X,
with VIII.
V with IX, and VI
Suppofe
HAZARDS of Game. 47
Suppofe then VII be the Main : To find
the proportion of the hazard of the Cafter
to that of the Setter.
By the Law of the Game, the Carter,
before he throws next, has four Chances
for nothing, viz. thefe II, III, XII ; eight
Chances for the whole Stake, viz. thofe
of VII, XI ; fix Chances for I., viz. thofe
IV, X ; eight Chances for -J-, viz. thofe
of V, IX -, and ten Chances for T S T , viz.
thefe of VI, VIII -, fo his hazard, by the
preceding Theorem, is
4x0-4-8x1 + 6x j- -4- 8 x-J- -f- 10 x T V
~
Now to fave the trouble of a tedious
reduction, fuppofe the Stake which they
play for be 36, that is, the Setter had laid
down 1 8 ; in that cafe, every one of
thefe Fractions are fo many parts of an
Unit/ which being gather'd into one Sum,
give 17*4 to the Cafter, leaving 1814 to
the Setter ; fo the hazard of the Cafter is
to that of the Setter 244, 251.
Suppofe VI, or VIII, be the Main, then
the Share of the Cafter is
JI.
III. VI. IV. V.
XL XII. X. IX. VIII. VII.
leaving
48 Solution of the
leaving to the Setter 18^. ; fo the hazard
of the Carter is to that of the Setter as'
6961 to 7295.
Suppofe V, or IX be the Main, then the
Share of the Carter is
II.
III.
XI. IV. VI.
XII. V. X. IX. VIII. VII.
6xo-f 4x i+6x
leaving to the Setter i8 T VV > f the hazard
of the Carter is to that of the Setter as
1396 to 1439.
It is plain, that in every cafe the Ca-
rter has the Difadvantage, and that V, or
IX, are better Mains to fet on than VII,
becaufe, in this laft Cart, the Setter has
but 1 8 and -J4> or jVo-J whereas, when V
or IX is the Main, he has 183- ; likewise
VI, or VIII, are better Mains than V, or
IX, becaufe .J-yJ. is a greater Fraction than
TTT-
All thofe Problems fuppofe Chances,
which are in an equal probability to hap-
pen > if it fhould be fuppos'd otherwilc,
there will arife variety of Cafes of a quite
different
HAZARDS of Game. 49
different nature, which, perhaps, 'twere not
unpleafant to conlider : I ihall add one Pro-
blem of that kind, leaving the Solution to
thofe who think it merits their pains.
In Parattelipipedo cujus laterafunt ad in-
i)icem in ratione a, b, c : Invenire quota vice
quivisfufcipere poteft, ut datum quodvis fla-
num, v.g. nbjaciaf.
A
DEMONSTRATION
O F T H E 4
Gain of the BANKER
In any Circumftarice of the
Game call'd Pharaon*
And how to determine the '
Odds at the ACE of HEARTS,
or FAIR CHANCE ;
With the ARITHMETICAL SOLUTION of
fome Queftions relating to LOTTERIES:
-And a few Remarks upon HAZARD and
BACKGAMMON,
L S3 J
Of the Game of PH A R A o N.
N order to demonftrate the Odds
or Gain of the Banker in any
circumftance of the Game of
Pharawi, it will be neceflary to
folve the following Problem.
P R O B. I.
Two Perfons A, B, out of a heap of 9 Cards,
four of which are red and five black, un-
dertake to draw a red one blindfold^ ' and
he fiall be reputed to win that draws the
firft : Now fuppofmg A to have the firft
choice,, B the jecond, A the third, and Jo
on by turns till one of them wins ; Qusere,
'The proportion of their Hazards ?
SOL u TION.
Let n be the number of ail the Cards, r
the number of red ones, b the number of
black
54 Of the Game
black ones, and i the whole Stake, or the
Sum play'd for.
i, Since A has r Chances for a red Card,
and b Chances for a black one, it follows
by the third Propofition that his Expe&a-
tion is worth -^ b or of the Stake, e-
qual to x i ; and accordingly let it be
agreed between the two Gamefters, that
inftead of yfs attempting to draw a red
Card he mall actually take out a black one,
and as an equivalent mall have -^ paid him
out of the Stake, which being done, there
will remain i = ^^ =- .
n n n
2, Since the remaining Cards are # r,
and B has r Chances for a red Card, it fol-
lows that his Probability of winning will be
-^ , and confequently his Expectation
upon the remaining Stake will be -~
x = - Butinfleadof B'sdraw.-
n n x n I
ing, we will fuppofe the Sum ny j n ^ l paid
him out of the Stake, and that a black
Card being taken out of the heap as before,
then the remaining Stake will be ^
rb bxn i b x n b bxb i
X I X i """ X I """"*" x n l *
3;
of PHARAON. 55
3% Now it comes to 4's turn again to
chufe ; and fince he has ftill r Chances for
a red Card, and the number of remaining
Cards are n 2, his Probability of winning
this time will be - , and his Expectation
upon the remaining Stake a * a ~| will be
~* ~ ' * ~r > which we will likewife
fuppofe to be paid him out of the Stake,
and then there will remain ""?. --.
n-n.ii l
3x3 i x r 3x3 jx 2
xg ^ , or nxn _ l x a "
b X b IX b bxb ix3 2 c
== - OUt Of
X a I X 2 - X I X 2 7
1-1 T-. 1 3x3 1x3 2Xr
which B may have
IX 2X 3
and fo we may proceed till the whole Stake
is exhaufted.
But I hope what has been faid is fufficient
to fee the Law of Continuation, and form
this general Series ; viz. - -f- - P -j-
+ :S,r. In which
'tis evident that P, Q^, R, S, &c. denote
the preceding Terms. Now to apply this
Series to practice, we muft take as many
Terms of it, as there are Units in b -\- i ;
for fince reprefents, the number of black
Cards, the number of Drawings cannot
exceed b -J- 1 3 therefore take for y^the firft,
56 Of tie Game
third, fifth, &c. Terms ; and for B, rfie
fecond, fourth, fixth, &c . Terms, and the
Sum of thole Terms will he the refpeclive
Expectations of ^, B$ or becanfe the Stake
is rix'd, thefe Sums will be proportional to
their refpedivc Probabilities of winning.
For inftance, if we apply this to the pre-
fent Cafe, the general Series will be -f-
4? H- fQ^r- yR.-f- yS -f- iT. And to
bring this Series into whale Numbers, let
us aSurne x a whole Number, which mul-
tiply'd by % ihall be a whole Number =3 P.
Therefore fmce ^ = P, ^ x-J-s=Q^an4
~ x 4 x f = R, &c. each of which Terms
are to be whole Numbers: Now 'tis evi-
dent that the Denominator of the Fraction
reprefented by P, is an aliquot part of that
reprefented by Q5 and every Denomina-
tor an aliquot part of the next following,
and fo the laft Denominator 9x8x7 x6x
5 x 4 is a Multiple to all the preceding De-
nominators; and confequently if each Nu-
merator be multiplied by it, inftead of x y
and the Produces divided by their refpective
Denominators, the Quotients will all be
whole Numbers, this is univerfally true :
But in this Cafe, if the laft Fraction
9x8x7x6x5x4
9/2. 7?6 3 * ts Denominator 126 is the leaft
common,
1
0/PHARAON. 57
common Multiple to all the reft of the
Fractions when reduc'd to their leaft Terms.
Which being determin'd, the Terms of
the Series are eafily found by the following
Operation to be 56 -f- 35 -4- 20 4- 10 -4-
4-M-
OPE RATION.
126 20 = R
504 60
9 ) - 6)
56=? 10 = 8
280 ~20~
8) - 5)
4 i
140 4
7) - 4)
20 == R i =s U
Wherefore aligning to ^ 56-4-20-4-4 = 80
And toB -------- 35^10+1 = 46
And their Probabilities of winning will be
as 80 to 46, or as 40 to 23. And if there
be never fo many Gamefters A, B, C, D,
&c. the Probabilities of winning may 'as
eafily be affign'd by the general Series, as
for thefe two.
1 REMARK^
Of the Game
REMARK.
The preceding Series may in any par-
ticular Cafe be eafily fhorten'd; for if r=i,
then the Series will be
'
If r = 2, then the Series will be -
n x n I
x -i -+- n 2 -+- n 3 -f- n 4, &c.
If r=^, then the Series will be
X .. --: X 2
x n i xw 2 -j-# 2 x 3 4-# 3 x 4
&c.
If r = 4, then the Series will be
1 X n ixa 2X/; 3 -J- 2X jX/z 4.
&C.
Wherefore rejecting the common Multi-
plica tors, the feveral Terms of thofe Series
taken in due order will be proportional to
the feveral Expectations of any number of
Gamefters. Thus in the Cafe of this Pro-
blem, where 72=9, ^ = 4, =5, the
Terms of the Series will be
For A. For B.
8x7x6 = 336 7x6x5 = 210
6x5x4 = ' 20 5x4x3 = 60
4x3x2 = 24 3x2x1 = 6
480 276
Hence
of PHARAON. 59
Hence it follows, that the Probabilities
of winning will be refpe&ively as 480 to
276, or dividing both by 12, as 40 to 23,
the fame as before,
The Game of PHARAON.
Rules of the Play.
Firft, The Banker holds a Pack of 52
Cards.
Secondly, He draws the Cards one after
the other, laying them alternately to his
right and left-hand.
Thirdly, The Ponte may, at his choice, 1
fet one or more Stakes, upon one or more
Cards taken out of his parcel of 13 Cards,
from the Ace to the King inclufive, call'd
a Book* either before the Banker has begun
to draw the Cards, or after he has drawn
any number of Couples, which are com-
monly call'd Pulls.
Fourthly, The Banker wins the Stake of
the Ponte, when the Card of the Ponte
comes out in an odd place on his right-
hand ; but lofes as much to the Ponte
when it comes out in an even place on his
left-hand.
Fifthly, The Banker wins half the Ponte's
Stake, when in the fame pull the Card of
the Ponte comes out twice.
I 2 Sixthly,
60 Of the Game
Sixthly, When the Card of the Ponte,
being once in the Stock, happens to be the
Lift, the Ponte neither wins nor lofes.
Seventhly, The Card of the Ponte being
but twice in the Stock, and the two laft
Cards happening to be his Cards, he then
lofes his whole Stake,
PR OB. II.
$0 find at Pharaon the Gain of the Banker >
when any number of Cards remain in
the Stock ; having the number of times that
the Ponte 's Card is contain d in it, given.
WHerefore this Problem admits of four
Cafes, fince the Ponte's Card may
be contain'd either once, twice, thrice, or
four times in the Stock,
Solution of the firfr, CASE.
The Banker, according to the Law of
the Game, has the following number of
Chances for winning and lofmg ; viz.
i Chance for winning i
i Chance for loiing i
i Chance for winning i
i Chance for lofmg i
i Chance for winning i
i Chance for lofmg o
Hence
of PHARAON* 6*
Hence the Banker has one Chance more
for winning than for lofing, and the num-
ber of all the Chances are equal to , the
number of Cards in the Stock j therefore -1
33 the Gain of the Banker upon the Stake.
To illuftrate this Cafe,
Let it be required to find the Gain of
the Banker, when there are 20 Cards re-
maining in the Stock, and the Ponte's Card
but once in it, =3
n 20
He gains the twentieth part of
his Stake.
Solution of the fecond CASE.
By the Remark belonging to the pre-
ceding Problem, it appears, that the Chances
which the Banker has to win or lofe his
Stake would be proportional to thefe Num-
bers n i, n 2, n 3, &G. were the
Banker not aliow'd half the Stake upon
drawing of Doublets, or the Ponte's Card
twice together ; upon which account the
number of Chances reprefented for the Ban-
ker by i for winning, mufl be divided
into two parts 2, and i, whereof the
firil is proportional to the probability which
the Banker has for winning the whole Stake
of the Ponte, and the fecond is proportional
to the probability of winning the half of it:
for fmce the Banker is not intitled to the
i whole
62 Of the Game
whole Stake upon the Ponte's Card coming
out in an odd place, till he knows whether
the next Card be the Ponte's, his Chance
for winning the whole Stake can be no
greater than the Ponte's ; becaufe there is
the fame reafon, and eafily prov'd, that the
fecond Card, and not the firft, mould be
the Ponte's, as the firft Card, and not the
fecond. Wherefore the Chances that the
Banker and the Ponte have to win the whole
Stake are equal, with refpect to the order
of drawing, and confequently mould be ex-
prefs'd by the fame number 3 whence arifcs
this Scheme for determining the .number of
Chances which the Banker has for win-
ning and lofing the Stake, and the num-
ber of Chances for winning the half Stake,
jeprefented by_y.
SCHEME.
\ ~" Chances for winning \
n 2 Chances for lofing i
4 ^ J-Chances for winning^
n 4 Chances for lofing i
^-Chances for winning^ I
n 6 Chances for lofing i
i Chance for winning i
Firft,
Of PH ARAON. 63
Firft, $r^r- = Number of Chances for
gaming y from the nature of the Scheme,
and n x ^^ = Sum of all the Chances.
Therefore -" ~~ 2 - is the probability of the
. r X I J
Banker's gaining^, and n ^ n __ l x7=the
Banker's Gain upon y.
Secondly, The Banker has but i Chance
more to win the Stake than to lofe ; the reft
for winning and lofmg being equal deftroy
each other. Therefore - is the pro-
/; l A
n x
2
bability of getting it, and - ~ x i =
n x
VJ ff i Z
- - is his Gain upon the Stake.
a x n i
Therefore the Banker's Gain vipon the
i i 2 2 ti '2. X -, -4- 2
whole is - - '
*" -r- ' -r i
MX ! j li y f
To illuftrate this Cafe by an Example in
Figures, Let it be required to find the Gain
of the Banker when there are 2d Cards
remaining in the Stock, and the Ponte's
Card twice in it.
fe = :-^=TVV = y T nearly.
Anfaer, About the thirty-fourth part of
his Stake.
That
64 Of tie Game
That x ^ J- is the Sum of all the
2
Chances, may be thus prov'd. 'Tis evi-
dent by infpection of this Scheme, that
they are equal to this Series n I, n 2,
n __ o n 4, &c. And - x
^ ? K x a i
i -f- 2 -h n 3, &c. is a Series-
belonging to the preceding Problem, which
exprefles the Sum of the Probabilities of
winning, which belong to the two Game-
flers, when the number of all the Cards is
72, and the number of red ones two. It
therefore exprefles like wife the Sum of the
Probabilities of winning which belong to
the Ponte and Banker in the prefent Cafe,
there being two of the Ponte's Cards in
the Stock ; but the Sum of thefe Probabili-
ties of winning are equal to Unity, becaufe
the Numerators of thofe Fractions which
exprefs their refpective Probabilities of win-
ning being added together, is equal to the
common Denominator, and fo equal to ah
Unit, confequently
x l_ , x i + 2 -f- 3, &c.
is equal to an Unit ; wherefore putting
/= i, n 2, n 3, &c. we mail
have -^i x/= i, and therefore /=
H^ I
x "T"'
Solution
65
Solution of the third CASE.
By the preceding Problem, the number of
Chances the Banker has for winning or lofing
the Stake would be proportional to thefe
Numbers n i x ;; 2, n 2 x # 3,
&c. but that on account of the Doublets,
the Banker's Chances for winning, as in the
preceding Cafe, are divided into two parts :
For inftance, n i x # 2 is divided imo
the parts n 2 x n 3, and 2 x n 2 ;
the former of which is proportional to the
Chances that both Banker and Ponte have
to win the whole Stake the firft pull, be-
caufe there is the fame probability that the
Ponte's Card mould be drawn the fecond
time and mifs'd the firft, as drawn the firft
time and mifs'd the fecond ; and the latter
part, viz. 2 x n 2 is proportional to the
Chances for both firft and fecond Cards be-
ing the Ponte's the firft pull : and as 2 x/z 2
is eafieft found by fubtracling n 2 xn 3
from ;/ i x n 2 ; fo by fubtracting
n 4 x n 5, the number of Chances that
the Banker and Ponte each have, for winning
the whole Stake the next pull from n i
x n 4, there will remain 2x;z 4, the
number of Chances for the third and fourth
Card being the Ponte's, and fo for the reft :
whence is eafily deduc'd the Method of
K forming
66 Of tie Game
forming' the following Scheme, which mews
what Chances the Banker has for winning
and lofing.
SCH EME.
2
f-2x~ 3 ? CI f j Ji
c 2 x n 23 ly
n 2 x n 3 Ch. for lofing i
4*-4*-5lch .for win .
C. 2 x n 43
n 4 x n 5 Ch. for lofing i
f ;
i x n C v
6 x 7 Ch. for lofing i
Hence it appears, that there are no more
Chances for winning the Stake than for lofing
it j fo all the Banker's Advantage in this
cafe is upon the half Stake, which depends
upon drawing of Doublets at one of the
Pulls, and all the Chances he has for that
may be found thus.
By the above Scheme, 2 x n 2 is the
firft Term of the Series to win v, 4 is the
common difference of the reft of "the Terms,
and 4 the laft Term j and fo the Sum of
all the Terms by the known Laws of Arith-
metical Progreflion is " x n ~ 2 , which di-
vided
RAON. 67
vided by the Sum of all the Chances =
* x " "~ '- ^-^- by the preceding Problem,
gives ~~rr~ f r l ^ e probability of win-
ning y ; therefore 2 x j*_ t x y is the Ban-
ker's Gain, equal - x< 3 _- , fuppofing ^=4.
EXAMPLE.
Query, The Banker's Gain when the Stock
confifts of 20 Cards, and the Ponte's Card
thrice in it ?
4X i 4 x 19 ~~ fT *" ~ 7T '
Anfwer, About the twenty-fifth part of
his Stake.
Solution of the fourth CASE.
SCHEME.
{^ rCh. for win.
3 x 2 x n 3 3 c y
2 x 3 x n 4 Ch. for lofing i
-67 ch f C i
3 x 4 x 5-) c^
4 x 5 x n 6 Ch. for lofing i
iy
2 x i x o Chance for lofing
K^2 HeTe
68 Of the Game
Here alfo the Chances for winning and
lofing the Stakes are equal, fo that the
Banker's Gain depends upon y y the half
Stake.
And the Chances to win y are
13x2x1! r 2 x i
Equal to<3x4x3> = 3x<4x3
03x6x5) C 6 * 5
&c. &c.
And to find the Sum of thofe Produces,
viz. 2x1 -4-4x3 -4- 6x5, &c. continued
to any number of Terms, whofe Factors
are in Arithmetical Progreffion, we muft
premife the following
LEMMA.
Subtract the fecond Product from the
third, and the third Product from the
fourth, and call the Remainers firft Diffe-
rences j then fubtract thofe Differences from
each other, and call the Remain er a fecond
Difference. See the following Scheme.
2X1= 2
1* I2 l8 Q
6x5 = 30 8
8 x 7 = 56
Now if we call the firft Product a, the
fecond b, the firft of the firft Differences /,
*he fecond Difference /'; and if the num-
ber
0/PHARAON. 69
ber of Products which follow the firft be
called x, the Sum of all the Products will
be equal to a -f- x x I - -f- ' x ^ ^ x / -f-
-Y X I X 2 ;
x x x a .
I 2 3
Or
* x
12 4- -f x ^ x 18 4-
X 2 Q
x x 8.
Or
2 4- 5-lx 4- 5** 4- i^xxx, which mul-
tiplied by 3, the common Multiplier to all
the Terms, the Product 6 4- 17*4-; 15**
4- 4# 3 will be the Sum of all the Chances
for winning of y, whofe component Parts,
by Sir IJ'aac Newton's Method of the Inven-
tion of Divifors, is readily found to be
2x -f- 2, 2x -+- 4, and 4Af 3 ^ wherefore
3
l2L is the number of
Chances for winning ofy. Now A; = to the
number of Terms to be added, bating i,
therefore make #-f- i=/>, equal to the
number of Terms, and then the Chances
for winning of y are .'/"H-'xiFT fi|Jt
according to the Scheme it appears, that
the number of Terms to be added are equal
to ^ ^ > wherefore writing ^ ^ for/,
and
70 Of the Game
and the Chances for winning are equal to
5 , which divided by the Sum
of all the Chances, viz. *Z^m-***-3
and the Quotient n _^"~ t *_ is the proba-
bility of winning y. and ib zn ~~ ; x ^ \*
J n i x 3
the Gain of the Banker, or - 2 """" 5 _
2 X - IXK - 3
fuppofing y = 4.
EXAMPLE.
Suppofe the Stock to confift of 20 Cards,
and the Ponte's Card four times in it ;
y The Banker's Gain ? \\
2 X n IX -^3 2x19x17 "" ~~ 'BT*' TT
nearly.
Anfiver^ T y T of his Stake accurately, or
the eighteenth part of it nearly.
of PHARAON. 71
A Table of Pharaon, whereby the federal Ad-
vantages of the Banker ', in whatever Cir-
cumftances he may happen to be^ isfeenfuf-
ficiently near by injpetfion, being calculated
Jrom the foregoing Theory.
I* Of
Cards
n the
Stock.
The N of times the Ponte's
Card is contain 'd in the Stock.
But
I
2
3
4
S^
50
4 B
46
44
_42_
40
38
Jl
34
-11
30
# *
18"
46
44
~94~
90
86
82
IL
74
70
66
62
Ji
54
"6T
62
60
57
54
5 2
49
46
L
41
3
50
48
_46_
44
Jf_
40
JL
36
34
3 2
30
28
42
40
3
J6_
34
ji
3
28
"26"
28
2b
S^
46
_^
33
26
24
i 24
22
2O
~7cT
" 16
~M~
12
IO
8
J
22
2O
"T8~
"76"
14
42
_ii
34
3^
30
28
2S
22
2O
J 7
22
20
IF
16
Hi
12
10
T
26
22
~TT
14
12
14
12
Q
1C
8
n
6
72 Of the Game
But if an abfolute degree of exactnefs be
required, it will be eafily obtain'd from the
Rules and Examples given at the end of
each Cafe. However, to make all things as
plain as poffible, I mail, to illuftrate the Ufe
of this Table, give an Example or two.
EXAMPLE i.
Let it be required to find the Gain of the
Banker when there are 30 Cards remaining
in the Stock, and the Ponte's Card twice
in it.
In the firft Column feek for the Num-
ber anfwering to the number of Cards re-
maining in the Stock : over-againft it, and
under number 2, which is at the head of
the Table, you will find 54, which mews
that the Banker's Gain is the fifty-fourth
part of his Stake.
EXAMPLE 2.
Let it be required to find the Gain of the
Banker when there are but 10 Cards re-
maining in the Stock, and the Ponte's Card
thrice in it.
Again ft 10, the number of Cards in the
firft Column, and under number 3, you
will find 12, which denotes that the Ban-
ker's Gain in this Circumftance is the twelfth
part of his Stake.
COROL-
of PHARAON. 73
COROLLARY i. From the Con ftruc-
tion of the Table it appears, that the fewer
Cards there are in the Stock, the greater is
the Gain of the Banker.
C o R o L . 2 . The lead Gain of the Ban-
ker under the fame circumftance of Cards
remaining in the Stock, is, when the Ponte's
Card is but twice in it, the next greater
when three times, ftill greater when but
once, and the greateft of all when four
times.
Of
74 Of the ACE (/HEARTS ;
Of the A c E of H E A RT s, or FA i R
CHANCE.
THIS Game is pretty much in vogue,
as well as that of Pharaon ; there-
fore it may not be improper here to touch
a little upon the Advantage or Gain that
accrues to the Banker or Taliere at this, as
well as of that.
The manner of playing at it is as follows ;
There is a Table, on which is painted a
felect number of Cards, generally 31 or 25,
or between thofe Numbers, limited at the
fancy of the Perfon who banks the Table ;
the Player flakes upon either of fuch Cards
more or lefs, at his pleafure. On the Table
is fixed an Engine, called a Worm, into
which is put an Ivory Ball, which runs
round till it drops or falls into a Socket
contiguous to one of thofe Cards; and if
it happens to be the Card on which the
Player has flaked, he faves his Stake, and
is intided to 28 or 23 times as much more,
according to the number of Cards painted
on the Table, and the cuilom of the Place
where
dr FAIR CHANCE. 75
where the Table is kept. From which De-
fcription of the Game, the following Pro-
blem naturally arifes.
P R O B. III.
ffie number of Cards upon fuch a Table ', and
the number of Stakes the Ranker pays in
cafe he fafes, being given ; to find the Gain
of the Banker upon any Siim depofited as
a Stake.
RULE.
FROM the number of Chances or Cards
the Table confifts of, fubtract the num-
ber of Stakes more by one than the Banker
pays when he lofes, and multiply the Re-
mainer by the value of the Stake^ and di-
vide the Product by the number of all the
Chances or Cards upon the Table, and the
Quotient will be the Banker's Gain upon
that Stake, and of the fame Denomination
with it ; confequently upon two Cards h6
will have twice that Advantage, upon three
Cards thrice, Gfc . foppofing the Stakes equal.
EXAM. i.
Suppofe a Table confifts of 31 Cards,
and that the Banker pays 28 Stakes when
he lofes ; %uery> His Advantage upon a
Stake of 100 / ?
L 2 31
j6 Of the ACE 0/ HEARTS ;
3 1 The N of all the Chances.
29 The N of Stakes paid more
by one.
2 Difference.
Multiply by 100 the Stake.
31)200 (6 /.
186
20
31)280(91.
279
Anfwer> 61.
.
But this Rule is capable of determining
the Gain of the Banker when unequal, as
well as equal Stakes are fet upon two or
more different Cards, it being only to be
considered as fo many diftindl Operations.
EXAM. 2.
Suppofe A, J9, C play, and flake between
them ioo/. viz. A 50, B 30, 20 j Query,
The Advantage of the Banker?
or FAIR CHANCE.
77
5
2% 2 Difference,
30
93
7
20
3 1) 140(4 j.
124
,6
3 1
29
_ 20
31)58^(18*.
3 r
270
248
22
31)
2 Diff.
20
"40! I
20
Hence theC^l
Banker's ^B Ms
Gain upon CC J
Total Gain
2 5
The fame as before ; whence it follows,
that let the Money be ftak'd how you will,
that is, upon as many Cards in what fhape
foever you pleafe, the Banker's Gain will
be after the rate of 6 /. 9 T ' T per Cent, upon
all the Money ftak'd.
But
78 Of tie ACE of HEARTS;
But for the fake of a farther Illuftration,
let us fuppofe a Perfon to ftake One Pound
Sterling upon each Card, to the number of
3 1, wz. all the Cards upon the Table ; in
fuch inftance, 'tis plain, he's fure of win-
ning, or to receive 28 /. for one of the
Cards, and fave the Stake of that Card
which wins j but then 'tis alfo evident upon
the whole, that he mufl be a lofer two
Pounds, fincehe wins only 28, and lofes 30.
Wherefore by the Rule of Proportion it
Follows, that if in flaking 3 1 Pounds he
lofes 2, in flaking loo Pounds he will lofe
6 /. 9 T f _, which confequently is the Banker's
Gain. See the Operation.
/. /. /. /. s.
31: 2 :: 100 : 6. 9T ' T
100
31)200 (67.
186
20
31)280(9*.
279
Wherefore
or FAIR CHANCE. 79
Wherefore the Advantage per Cent, is fo
plain, that 'tis needlefs to dwell any longer
upon it : However, it may not be amifs to
obferve, that 'tis an equal Wager that any
one Card will win once in 2 1 times, notwith-
ftanding the number of all the Chances arc
3 1 i which Event is difcover'd in this or any
other Table, by this general
RUL E.
From the number of all the Cards upon
the Table, dedudt one, and multiply the
Remainer by feven tenths, and the Product
is the Anfwer. So in this Cafe,
31 1 =30
Multiply by ,7
21,0
And the Product 21 is the number of
Trials requifite for any one Car4 to win
upon an equality of Chance.
Of
So Of LOTTERIES.
O/*LOTTERIES.
IN this place I fhall confider the Solution
of feveral Problems relating to Lotteries,
which may be of ufe to prevent fome mif-
takes that People, not vers'd in fuch Com-
putations, frequently run into. For in-
ftance, in the prefent Lottery for the Year
1737, where the proportion of Blanks to
the Prizes is as 9 to i, 'tis natural enough
to conclude, that 9 Tickets are requifite for
the chance of a Prize ; and yet from mathe-
matical Principles 'tis evident, that 7 Tickets
are more than fufficient for that purpofe,
that is, in 7 Tickets it is more likely to
have a Prize than not : for this, and all
other Cafes of this nature, we {hall give
the Arithmetical Solution of the following
Problem.
PROS. IV.
To find how many Tickets mujl be taken, to
make it as probable that one or more Prizes
may be taken as not,
RULE
Of LOTTERIES. 81
RULE.
Multiply the number of Blanks there
are to one Prize by feven tenths, and the
Product is the Anfwer.
EXAMPL E.
Query, The number of Tickets requifite
in a Lottery, whereof the number of Blanks
is to the number of Prizes as 9 to i, to
make it an equal Chance for one or more
Prizes.
9
7
, The Product 6,3 mows there is
more than an equality of Chance in 7
Tickets, but fomething lefs than an equality
in 6.
EXAMPLE 2.
<%uery, The number of Tickets requifite
in a Lottery, whereof the number of Blanks
is to the number of Prizes as 5 to i, to
make it an equal Chance for one or more
Prizes.
5
>7
3*5
M Anfwer -,
83 Of LOTTERIES.
Anfwer, The number of Tickets requi-
fite to that effect is between 3 and 4.
PROS. V.
70 fold bow many 'Tickets miijl be taken, to
make it as pr.ebabti that five or more Prizes
will be taken as not.
R U L E.
Multiply 1,678 always by trip number of
Blanks there are to a Prize, and the Product
will be the Anfwer.
EXAMPLE.
How many Tickets mutt be had in a
Lottery, to make it as probable that two or
more Prizes will be taken as not, wheri
there are 9 Blanks to a Prize ?
1,678
9
Anfaer, More than 1 5 Tickets, or rather
more than 1 6, as mall be prov'd farther on,
tho' one might undertake upon an equality
of Chance to have one at leaf! in 7 Tickets.
7'he Numbers 0,7 and 1,678 made ufe
of to folve this and the preceding Problem,
is the refult of determining the Limits of %
in thefe Equations, war. a -\- b x = 2^,
and
Of LOTTERIES. 83
and a -f- b* = 2^* -f- iaxb x \ where
and reprefent the number of Chances re-
fpectively for the happening and failing of
an Event at any one trial.
'Tis not my defign to give a Solution to
both thefe Equations j but being determin'd
to find the Value of x in one of them, I
{hall undertake ^he laft, as apprehending
it will be mod: acceptable, efpecially to thofe
who are not very ready in folving exponen-
tial Equations.
X
a -\-b === 2b* -j- 2axb*~ l , becomes
^ = 2 -+- 2axlr- 1 by dividing both
b
fides of the Equation by b*. Make a : b ::
I : 7, and the laft Equaticn by fubftitution
becomes i -f- ~ = 2 -f- 2f , in which, if
q be fuppofed equal to J, x will be found
equal to 3 5 but if q be fuppofed infinite,
and = z, x will be infinite alfo, and
we mail have i -f- = 2x1-1-2?.
i ,
Again, the Hyperbolic Log. of i -f-
multiplied by zq is equal to the Hyperbolic
Log. of 2 -+- the Hyperbolic Log. df i -\- z.
But the Hyperbolic Log. of i -t- y multi-
plied by == i, therefore z == Hyperbolic
M 2 Log,
84 Of LOTT ERIES.
Log. of 2 4- the Hyperbolic Log. of
From which laft Equation z may be found,
for z log. i -H z = log. 2 = ,693 147
= n 5 but the Hyperbolic Log. of i -f- z
ZK z.3 z.4 c i r
== z -- - H ---- , &c. therefore
x ** * 4 ** e ii
~ "~~7 + T~~ T' &c -= ff > and b y
reverfing the Series z = ^/2n -f- -f-
to
1,678 nearly.
Hence the Value of x in all Cafes will
be between ^q and 1,6785' ; but AT converges
pretty foon to the laft of thofe Limits, and
fo the number 1,678, when x is not too
fmall, gives the Anfwer fufficiently exacft ;
as in the following Example, where the
Odds of the Event's happening is greater
than in the former.
EXAMPLE 2.
Let it be required to rind in how many
Throws, one may undertake upon an equa-
lity of Chance, to throw three Aces twice,
with three Dice ?
SOLU TION.
Out of the 216 Chances upon three Dice,
there is but i Chance for three Aces, and
215 againfl it ; wherefore multiplying the
above
Of LOTTERIES. 85
above Number 1,678 by 215, and the Pro-
duct 360,77 (hows, that 360 Throws, or
very near it, are requilite to produce the
required effect.
But when x is fmall, as in the preceding
Example, it needs a correction j for inflead
of 15,102 Tickets, it fhould be 16,443 :
which Correction is eafily had by the Rule of
double falfe Pofition. For being afTur'd that
x is found fomething too little, I therefore
affume it equal to 1 6, and fubftitute it in
the Equation i -f- - = 2 -+- and find
i i
the left-hand fide thereof lefs than the right
by 0,1589 -, wherefore I increafe the value
of x four tenths more, viz. to 16,4, and
fubftitute it in the Equation as before, and
{till find the left-hand fide too little by
0,0155; then I multiply crofs-ways, and
proceed in the reft of the Operation accor-
ding to the nature of the Rule, and find
#=16,443.
However, we are not deflitute of a Me-
thod whereby the true value of z, and con-
fequently that of x may be found directly,
by the help of an infinite Series, viz. ~
+ l? + y^ 3 > &c - For P u ing the
Hyperbolic Log. of i H = m t mq
= r, the fhnding Quantity 1,791759
86 Of LOTTERIES.
= n, and 2.mq n = s. The firft T" errri
of the Series, i>/;s. lubtradled from 2,
will give the value of z in this cafe, true
to two places of Decimals^ viz. 1,83, whence
1,83 x 9 = 16,47 ' ls tne va ^ ue f *> or
true number of Tickets very near ; for three
Terms of the Series make x = 1 6,44300.
And if x be fmaller ftill, but fo as not to
have the number of Blanks to a Prize lefs
than 4,1473 (which feldom or never hap-
pens in Lotteries) more places of Decimals
will turn out true ; in mort, the above Series
will determine the Value of z all Cafes, when
q is between 4,1473, and any other num-
ber how great foever.
Though, as it has been obferv'd before,
when q. is any thing large, 1,678^ gives
x fufficiently near ; for two Terms of this
Series, in the cafe of throwing three Aces
twice with three Dice, make z === 1,686,
and confequently x = 1,686 x 215 =
362,49, which is not two throws more
than by the former Computation.
Nofe, The Solution of this Equation, viz.
a -+- b = zb* -4- 2xab x ~ l -|- x x x i
x a'-b* 2 will give the value of x, in the
Cafe of a triple Event ; and the Solution o'f
this, viz. a + b = 2$* -f- 2xab x I -f- x
x ^ ^ x ^^a>lf x ^3
will
Of LPTTERIE s. 87
will give the value of x in the Cafe of a
quadruple Event. Here follows a Table of
the Limits of x from one to fix Events in-
clufive.
The Value of x will always be,
I
<
ffmgle
double
1 f if]
g I 37
0,693?
1,678?
,
quadruple i
quintuple
P R o B. VJ.
The 'Number of Tickets a Perfon has in a
Lottery being given, to find the Odds again ft
him whether they a// prove Prizes.
RULE.
To the number of Blanks to a Prize add
T, and make the Sum the Denominator of
a Fraction whofe Numerator is Unity ;
then multiply this Fraction continually into
itfelf as often as the Perfbn has Tickets in
the Lottery, bating one, and from the laft
Fraction thus produc'd, if Unity be taken
from its Denominator, the Remains will
fhew how many to I it is, that thsy all
prove Prizes.
EXAMPLE,
88 O/* LOTTERIES.
EXAMPLE.
Suppofe I have three Tickets in the Lot-
tery of this Year 1737, where there are 9
Blanks to a Prize ; how many is it to one
but that they are all Prizes r
9 -4- i = 10 the Denominator.
v I v I
To" x To" X TTT Too"o'
Answer, 999 to i.
N. B. This Rule is only applicable to
Lotteries, or in Schemes where there are a
great number of Blanks and Prizes.
PROS. VII.
Having the Number of Tickets, and the Num-
ber and Amount of all the Prizes undrawn
(it any time given, to find the Value of a
Horfefor any number of Days.
RULE.
Multiply the number of Prizes by the
Price of an undrawn Ticker, and fubtract
the Product from the Amount of all the
Prizes, and multiply the Remainer by the
number of Days the Horfe is hired for, and
referve the Product for a Dividend ; then
multiply the number of undrawn Tickets
by the number of Days required to draw
them in, and with the Product divide the
aforefaid Dividend, and the Quotient will
s be the Value of the Horfe.
EXAMPLE.
Of LOTTERIES. 89
EXAMPLE.
Let it be required to find the Value of a.
Horfe for the firft Day's drawing in the"
prefent Lottery, where there are 70000
Tickets at lo/ each, number of the Prizes
7000, amounting to 22^000 /. exclufive of
the two Prizes for the firft and lafl Num-
bers drawn, viz. 500 and iooo/. arid let
us fuppofe that the whole time of Drawing
will be 40 Days. '.U
The N of Prizes ^ -- -----
Price of an undrawn Ticket - - 10
70000
The N of undrawn Tickets 70000
The whole time of drawing - 4.0 d.
2600000
The Amount of all the Prizes; deduc-
ting 14 per Cent, is 1943607.
194360
70000
2800000) 124360,000 ( ,044
I 1200000 20
L 5 88o
12360000
"30000
Il6oOCO r
/2 3 2 4
Anfaer, i o d. |.
N Thofe
go Of LOTTERIES.
Thofe that do not chufe to divide deci-
mally, may, if they pleafe, multiply the
aforefaid Dividend by 960 before they di-
vide, and the Quotient will be the Anfwer
in Farthings -, e . g.
124360
960
7461600
1119240
28)00000) 1 193(85600
~42~~ ""112
4) 73
101 56.
17
Which i o A. 4- would be the real Value
of the Horfe j but as it's on the firft Day's
Drawing, there is a probability of its being
the firft drawn, in confequence of which
the Owner is intitled to a Prize of 500 /. this
Expectation is worth about three Half-Pence
more, 'viz. the 70,000 part of the Value of
500 /. when the 14 per Cent, is taken off,
which being added to the Value before
found, makes i Shilling, the mathematical
Value of a Horfe for the firft Day's drawing.
EXAMPLE 2.
Admit that 1 2 Days before the end of
the Drawing, there are left in the Wheel
of
Of LOTTERIES. 91
of Fortune 20544 Tickets, of which 2100
are Prizes, amounting in all to 714007.
Query ', The Value of a Horfe for two Days,
the Price of an undrawn Ticket at that
time being worth 1 1 Pounds.
The Amount of all the Prizes, deduc-
ting 1 4 per Cent, is 61404 Pounds.
The Number of Prizes . . 2 1 oo
The Price of an undrawn Ticket 1 1
2100
2100
23100
The Number of undrawn Tickets 20544
Number of Days to draw them in i_z
246528
61404
23100
246528)76608,000 ( ,310
739584 _20_
1 S. 6,200
264960 12
246528
l8 43 20
Anfwer> 6 s, ^d. .
N 2 Note,
ga Of LOTTERIES.
Note, Irrthefe Calculations' 'tis fuppofed^
(as is cuftomary) that if the Horfe proves
a Prize during your Jockeyfhip, that i o /.
or an undrawn Ticket be rtftur'd to the
perfon who let it.
It is alfo very plain that this Rule will
ferve to value the Chance of a Ticket du-
ring the whole Lottery, aJlume the number
of Days it will take in drawing what ycu
pleale -, wherefore to render' the Opera uon.
ea'fy, fuppofe i Day. ' Ar.d altho* I have
made a deduction of \^per Cent, upon the
Amount of all the Prizes in the two pre-
ceding Exr.mples, and at the fame time
allow the Calculation to ue Agreeable to the
kules of Art and Science, as being founded
on the ftricttft Demonflration j yet in the
preferit Cr.f ..-, I lay, the Dedudion is not
quite realbnable between Buyer and Seller,
and confequently none fhould be made in
finding the value of a Chance for the whole
time : Foi how can irbe expected that any
one will give up his right in a Ticket if it
proves a Prize, and fbnd to the lofs of a
Guinea extraordinary' if it proves a Blank,
uiz. the Djfcount upon 7 /. i o s. at the rate
of i^per Cent, without a valuable coniide-
ration, which is that of taking Chances,
valued according to the full Amount of the
Prizes, and the Price the Tickets bore when
they were firft purchas'd, viz. io/. each.
Of LOTTERIES. 97
This Method of proceeding will put both
Parties upon an equal footing, than which,
I think nothing can be more fair and equi-
table.
Hence I make the Chance of a Ticket
for the whole time of drawing to be worth
2 /. 4*. 6J. , which, with 2d. f for the
Expectation of its being either the firft or
laft drawn, makes 2/. 4*. gd. f ; but if
the Chance happens to prove a Prize, io/.
more, or the Price of an undrawn Ticket
muft be advanc'd. -However, the Market-
price determines what muft be given after
all ; wherefore if a Chance mould fell for
more than what this Calculation makes, it
is not to be wonder 'd at, fince fome con-
iideration ought to be made for the rifque
that the Dealers in Tickets run in having
them fold under par, and for fome con-
tingent Expences they are unavoidably at,
in furnifhing thofe with Chances and Tickets
who are willing to be in Fortune's Way.
But as in all Lotteries Succefs is preca-
rious, we being kept in fufpence till the
Event makes known either our good or
bad Fortune, fo from luch ftate of Uncer-
tainty it follows, that before the Drawing
is finim'd a Ticket may be fold for more
or lefs than at prefent ; I mall therefore,
before I conclude this Subject, mew how
its real worth may be known in any cir-
2 cum fiance
94 Of LOTTERIES.
cumftance of the Lottery, by which means
the value of a Chance may be very accu-
rately determin'd at the fame time, e. g.
Multiply the Number of Blanks remain-
ing in the Lottery at any time of its draw-
ing, by the Price of a Blank, which is al-
ways fix'd, and to the Prbduct add the
Amount of all the Prizes remaining, the
laft drawn included; this Sum divided by
the Number of all the Tickets, izz. Blanks
and Prizes, will give the value of an undrawn
Ticket, which being known, the Value of
a Chance for the time, during the remaining
part of the Lottery, eafily flows from the
afore- mentioned Rule,
I mall conclude this fmall TracT: by ma-
king fome Remarks, relating to Hazard and
Backgammon j the truth of all which is
cafily deduc'd from the preceding
tions*
Of HAZARD. 95
Of HAZARD.
i. TF 8 and 6 are Main and Chance, one
J[ may lay 155 to 169, or u to 12,
that either one or the other is thrown off
in two Throws.
2. And if 5 and 7, or 9 and 7 are Main
and Chance, the probability of their being
thrown off in two Throws is alfo as 155
to 169, or as u to 12.
3. If 5 and 8, or 9 and 8, or 5 and 6,
or 9 and 6 are Main and Chance, the pro-
bability of throwing one of them off in two
Throws is as 7 to 9 exactly.
4. And if 7 and 4, or 7 and 10 are
Main and Chance, the probability of their
being thrown off in two Throws is alfo as
7 to 9.
5. If 7 and 8, or 7 and 6 are Main and
Chance, one may lay 671 to 625, or 15
to 14 that one of them is thrown off in
two Throws, fo he that lays an even Wager
he will throw one of them off in two
Throws has the beft of the Lay.
Of HAZARD.
6. But if 5 and 4, or 5 and 10, or 9
and 4, or 9 and 10 are Main and Chance,
he that undertakes to throw either Main or
Chance in three Throws has the worft of
the Lay ; for it is as 22267 to 24389, or
in fmaller Terms, as 21 to 23 exceeding
near ; the Ratio of 21 to 23 differing from
that of 22267 to 2 43^9 only but by the
ten thoufandth part of an Unit.
Note alfo, that n and 12 exprefs the
Ratio of 155 to 169 the neareft poffible in
fuch fmall Terms, as does 15 to 14 that of
671 to 625, and are eafily difcover'd by
the Rule exhibited in my Appendix to
Dr. Ketl's Euclid.
7. Suppofe IV to be a Main, and the
Law of the Hazard to be this ; That if the
Cafter throws either II, III, IV, XI, or
XII the fii-ft Throw, he mall lofe the whole
Stake, and if he throws V, VI, VII, VIII,
IX, or X, either of which, as it may hap-
pen, mall be deem'd a Chance againfr. IV,
fo which ever comes up firft wins ; Query %
The Hazard of the Cafter to that of the
Setter ?
Anjwer^ The Hazard of the Carter is to
that of the Setter as 457 to 551, or as 5
to 6 very near ; wherefore the Gain of the
Setter, each Stake being a Guinea, will be
T y_. equal to i s. 1 1 d. ? exactly.
8.
Of HAZARD. 97
8. And at Hazard, if the Main be y t
and each ftake a Guinea, the Gain of the
Setter is about 3^.
9. If the Main be 6 or 8, the Gain of
the Setter is about Six-pence in a Guinea.
10. But if the Main be 5 or 9, the Gain
of the Setter is about 3 d. -J- in a Guinea ;
whence it follows, that 5, 7 and 9 are
much upon a par to fet on, and that 6 and
8 are fomething more advantageous.
11. However, if a Perfon is determined
to fet upon the firfl Main that is thrown,
his Advantage, fuppoling each Stake to be
a Guinea, is the T |-rr f a Guinea, which
when reduc'd will be found equal to 4^. |,
and half a Farthing exactly.
12. Hence the probability of a Main, to
the probability of no Main ; or, to fpeak
in trie gaining Phrafe, a Main or no Main,
is as 2016 37 to 20 1 6 -f- 37 ; that is,
as 1979 to 2053 accurately, or as 27 to
28 very near ; for if one flakes 27 Guineas,
the other ought not to flake quite 2 d. -*-
more than 28 Guineas, which is a fmall dif-
ference from the truth in fuch large Stakes
as 27 and 28 Guineas.
13. If, with two Dice, one mould under-
take to throw firft the two Aces, next the two
Duces, next the two Threes, next the two
Fours, next the two Fives, and laflly the
two Sixes, the Odds again ft him would be
O
g8 Of HAZARD,
two thoufand, one hundred, and feventy-
fix Millions, feven hundred, eighty-two
thoufand, three hundred, and thirty-five
to one ; and tho' this might poffibly hap-
pen the firft fix throws, yet the Odds are
fo immenfely great againft it, that it Would
probably require whole Ages to perform
it in : yet notwithstanding all this difficulty
in throwing firft the two Aces, next the
two Duces, &c. they may with an equa-
lity of Chance be undertaken to be thrown
in lefs than a quarter of an Hour, in the
following manner, viz. to throw away till
the two Aces come up, then till the two
Duces, then till the two Threes, and fo on
till the two Sixes are thrown ; but to throw
them fucceffively is what, never yet, is ra-
tional to fuppofe,fcas been done by any one.
14. If any one mould undertake to throw
a Six or an Ace with two Dice in one
throw, he ought to lay 5 to 4, whereas
'tis ufual to lay an even Wager only; in
which cir cum fiance the Caller has fo much
the better of the lay, as in the long run to
impoverifh the beft Eftates, not to fay ruin
them. Tho' at firft fight it muft appear
to an Eye not vers'd in thefe Speculations,
a little odd, that the Setter mould not have
the beft of it, fince there are but two Sixe?,
and two Aces for the Cafter, and two Fives,
,two Fours, two Threes, *and two Ducesj
for
Of .BACKGAMMON. 99
for the Setter. And were the Points > of
both Dice all made upon a regular Solid or >
Body of 1 2 equal Faces, fuch as the Dode-'
caedron, the Cafter would undoubtedly have
the advantage ; for then he would have two
to one of the lay, in as much as he would
have 8 Chances for winning, 'and but 4 foV
lofing : But as there are two Dice, it mufl
be confidered as the happening of two
Events, independent of each other, which
makes the Odds, as I faid before, jufl 5 to
4-
Co^OLL AR Y.
Hence it follows, that 1 at 'Backgammon
if two Points are open, 'tis 5 to 4 but that
a Perfon enters the firft throw ; and as this
Thought naturally leads me to give a Solu-
tion of the reft of the Hazards, it may per-
haps be acceptable if I mew the Odds of en-
tring when other Points of the Table are
open, and therefore mall give the following
Scheme for that purpofe.
SCHEME.
Points open
A Perfon may lay
i
III' f2cf
2
3
jlj
i > that one enters.
4
. jf
35J
j]
And
ioo Of BACKGAMMON.
And I don't doubt, but the Knowledge
of thefe Odds may enable one to play the
Game in other refpeds with great advan-
tage j tho* for my part I own with regard
to pra&ice, that I have but very little ikili
in this, or any other Game whatfoever.
FINIS.
A 000 031 305 6