4/3/2022

Fletcher Formula Blackjack

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Fletcher Formula Blackjack 6,6/10 6882 reviews

Blackjack Forum is a friendly community where Blackjack players of all skill levels are welcome. Discuss basic strategies to card counting and advanced techniques like shuffle tracking in the Blackjack forums. Most online blackjack games have betting limits from $1 to $100. They do this for a reason – With low betting limits they prevent players with a high-powered blackjack strategy like the Fletcher Formula from being able to win high amounts every hour. Many players do quite well playing in the $100 max bet games.

In gambling parlance, making a book is the practice of laying bets on the various possible outcomes of a single event. The term originates from the practice of recording such wagers in a hard-bound ledger (the 'book') and gives the English language the term bookmaker for the person laying the bets and thus 'making the book'.[1][2]

Making a 'book' (and the notion of overround)[edit]

A bookmaker strives to accept bets on the outcome of an event in the right proportions in order to make a profit regardless of which outcome prevails. See Dutch book and coherence (philosophical gambling strategy). This is achieved primarily by adjusting what are determined to be the true odds of the various outcomes of an event in a downward fashion (i.e. the bookmaker will pay out using his actual odds, an amount which is less than the true odds would have paid, thus ensuring a profit).[3]

The odds quoted for a particular event may be fixed but are more likely to fluctuate in order to take account of the size of wagers placed by the bettors in the run-up to the actual event (e.g. a horse race). This article explains the mathematics of making a book in the (simpler) case of the former event. For the second method, see Parimutuel betting.

It is important to understand the relationship between fractional and decimal odds. Fractional odds are those written a-b (a/b or a to b) mean a winning bettor will receive their money back plus a units for every b units they bet. Multiplying both a and b by the same number gives odds equivalent to a-b. Decimal odds are a single value, greater than 1, representing the amount to be paid out for each unit bet. For example, a bet of £40 at 6-4 (fractional odds) will pay out £40 + £60 = £100. The equivalent decimal odds are 2.5; £40 x 2.5 = £100. We can convert fractional to decimal odds by the formula D=​b+ab. Hence, fractional odds of a-1 (ie. b=1) can be obtained from decimal odds by a=D-1.

It is also important to understand the relationship between odds and implied probabilities:Fractional odds of a-b (with corresponding decimal odds D) represent an implied probability of ​ba+b=​1D, e.g. 6-4 corresponds to ​46+4 = ​410 = 0.4 (40%).An implied probability of x is represented by fractional odds of (1-x)/x, e.g. 0.2 is (1-0.2)/0.2 = 0.8/0.2 = 4/1 (4-1, 4 to 1) (equivalently, ​1x - 1 to 1), and decimal odds of D=​1x.

Example[edit]

In considering a football match (the event) that can be either a 'home win', 'draw' or 'away win' (the outcomes) then the following odds might be encountered to represent the true chance of each of the three outcomes:

Home: Evens
Draw: 2-1
Away: 5-1

These odds can be represented as implied probabilities (or percentages by multiplying by 100) as follows:

Evens (or 1-1) corresponds to an implied probability of ​12 (50%)
2-1 corresponds to an implied probability of ​13 (33​13%)
5-1 corresponds to an implied probability of ​16 (16​23%)

By adding the percentages together a total 'book' of 100% is achieved (representing a fair book). The bookmaker, in his wish to avail himself of a profit, will invariably reduce these odds. Consider the simplest model of reducing, which uses a proportional decreasing of odds. For the above example, the following odds are in the same proportion with regard to their implied probabilities (3:2:1):

Home: 4-6
Draw: 6-4
Away: 4-1
4-6 corresponds to an implied probability of ​35 (60%)
6-4 corresponds to an implied probability of ​25 (40%)
4-1 corresponds to an implied probability of ​15 (20%)

By adding these percentages together a 'book' of 120% is achieved.

The amount by which the actual 'book' exceeds 100% is known as the 'overround',[4][5] 'bookmaker margin' [3] or the 'vigorish' or 'vig':[3] it represents the bookmaker's expected profit.[3] Thus, in an 'ideal' situation, if the bookmaker accepts £120 in bets at his own quoted odds in the correct proportion, he will pay out only £100 (including returned stakes) no matter what the actual outcome of the football match.Examining how he potentially achieves this:

A stake of £60.00 @ 4-6 returns £100.00 (exactly) for a home win.
A stake of £40.00 @ 6-4 returns £100.00 (exactly) for a drawn match
A stake of £20.00 @ 4-1 returns £100.00 (exactly) for an away win

Total stakes received — £120.00 and a maximum payout of £100.00 irrespective of the result. This £20.00 profit represents a 16​23 % profit on turnover (20.00/120.00).

In reality, bookmakers use models of reducing that are more complicated than the model of the 'ideal' situation.

Bookmaker margin in English football leagues[edit]

Bookmaker margin in English football leagues decreased in recent years.[6] The study of six large bookmakers between 2005/06 season and 2017/2018 season showed that average margin in Premier League decreased from 9% to 4%, in English Football League Championship, English Football League One, and English Football League Two from 11% to 6%, and in National League from 11% to 8%.

Overround on multiple bets[edit]

When a punter (bettor) combines more than one selection in, for example, a double, treble or accumulator then the effect of the overround in the book of each selection is compounded to the detriment of the punter in terms of the financial return compared to the true odds of all of the selections winning and thus resulting in a successful bet.

To explain the concept in the most basic of situations an example consisting of a double made up of selecting the winner from each of two tennis matches will be looked at:

In Match 1 between players A and B both players are assessed to have an equal chance of winning. The situation is the same in Match 2 between players C and D. In a fair book in each of their matches, i.e. each has a book of 100%, all players would be offered at odds of Evens (1-1). However, a bookmaker would probably offer odds of 5-6 (for example) on each of the two possible outcomes in each event (each tennis match). This results in a book for each of the tennis matches of 109.09...%, calculated by 100 × (​611 + ​611) i.e. 9.09% overround.

There are four possible outcomes from combining the results from both matches: the winning pair of players could be AC, AD, BC or BD. As each of the outcomes for this example has been deliberately chosen to ensure that they are equally likely it can be deduced that the probability of each outcome occurring is ​14 or 0.25 and that the fractional odds against each one occurring is 3-1. A bet of 100 units (for simplicity) on any of the four combinations would produce a return of 100 × (3/1 + 1) = 400 units if successful, reflecting decimal odds of 4.0.

The decimal odds of a multiple bet is often calculated by multiplying the decimal odds of the individual bets, the idea being that if the events are independent then the implied probability should be the product of the implied probabilities of the individual bets. In the above case with fractional odds of 5-6, the decimal odds are ​116. So the decimal odds of the double bet is ​116×​116=1.833...×1.833...=3.3611..., or fractional odds of 2.3611-1. This represents an implied probability of 29.752% (1/3.3611) and multiplying by 4 (for each of the four equally likely combinations of outcomes) gives a total book of 119.01%. Thus the overround has slightly more than doubled by combining two single bets into a double.

In general, the combined overround on a double (OD), expressed as a percentage, is calculated from the individual books B1 and B2, expressed as decimals, by OD = B1 × B2 × 100 − 100.In the example we have OD = 1.0909 × 1.0909 × 100 − 100 = 19.01%.

This massive increase in potential profit for the bookmaker (19% instead of 9% on an event; in this case the double) is the main reason why bookmakers pay bonuses for the successful selection of winners in multiple bets: compare offering a 25% bonus on the correct choice of four winners from four selections in a Yankee, for example, when the potential overround on a simple fourfold of races with individual books of 120% is over 107% (a book of 207%). This is why bookmakers offer bets such as Lucky 15, Lucky 31 and Lucky 63; offering double the odds for one winner and increasing percentage bonuses for two, three and more winners.

In general, for any accumulator bet from two to i selections, the combined percentage overround of books of B1, B2, ..., Bi given in terms of decimals, is calculated by B1 × B2 × ... × Bi × 100 − 100. E.g. the previously mentioned fourfold consisting of individual books of 120% (1.20) gives an overround of 1.20 × 1.20 × 1.20 × 1.20 × 100 − 100 = 107.36%.

Settling winning bets[edit]

In settling winning bets either decimal odds are used or one is added to the fractional odds: this is to include the stake in the return. The place part of each-way bets is calculated separately from the win part; the method is identical but the odds are reduced by whatever the place factor is for the particular event (see Accumulator below for detailed example). All bets are taken as 'win' bets unless 'each-way' is specifically stated. All show use of fractional odds: replace (fractional odds + 1) by decimal odds if decimal odds known. Non-runners are treated as winners with fractional odds of zero (decimal odds of 1). Fractions of pence in total winnings are invariably rounded down by bookmakers to the nearest penny below. Calculations below for multiple-bet wagers result in totals being shown for the separate categories (e.g. doubles, trebles etc.), and therefore overall returns may not be exactly the same as the amount received from using the computer software available to bookmakers to calculate total winnings.[7][8]

Singles[edit]

Win single

E.g. £100 single at 9-2; total staked = £100

Returns = £100 × (9/2 + 1) = £100 × 5.5 = £550

Each-way single

E.g. £100 each-way single at 11-4 ( ​15 odds a place); total staked = £200

Returns (win) = £100 × (11/4 + 1) = £100 × 3.75 = £375
Returns (place) = £100 × (11/20 + 1) = £100 × 1.55 = £155
Total returns if selection wins = £530; if only placed = £155

Multiple bets[edit]

Each-Way multiple bets are usually settled using a default 'Win to Win, Place to Place' method, meaning that the bet consists of a win accumulator and a separate place accumulator (Note: a double or treble is an accumulator with 2 or 3 selections respectively). However, a more uncommon way of settling these type of bets is 'Each-Way all Each-Way' (known as 'Equally Divided', which must normally be requested as such on the betting slip) in which the returns from one selection in the accumulator are split to form an equal-stake each-way bet on the next selection and so on until all selections have been used.[9][10] The first example below shows the two different approaches to settling these types of bets.

Double[11][12]

E.g. £100 each-way double with winners at 2-1 ( ​15 odds a place) and 5-4 ( ​14 odds a place); total staked = £200

Returns (win double) = £100 × (2/1 + 1) × (5/4 + 1) = £675
Returns (place double) = £100 × (2/5 + 1) × (5/16 + 1) = £183.75
Total returns = £858.75
Fletcher formula blackjack
Returns (first selection) = £100 × (2/1 + 1) + £100 × (2/5 + 1) = £440 which is split equally to give a £220 each-way bet on the second selection)
Returns (second selection) = £220 × (5/4 + 1) + £220 × (5/16 + 1) = £783.75
Total returns = £783.85

Note: 'Win to Win, Place to Place' will always provide a greater return if all selections win, whereas 'Each-Way all Each-Way' provides greater compensation if one selection is a loser as each of the other winners provide a greater amount of place money for subsequent selections.

Fletcher Formula Blackjack

Treble[11][12]

E.g. £100 treble with winners at 3-1, 4-6 and 11-4; total staked = £100

Returns = £100 × (3/1 + 1) × (4/6 + 1) × (11/4 + 1) = £2500

Accumulator[11][12]

E.g. £100 each-way fivefold accumulator with winners at Evens ( ​14 odds a place), 11-8 ( ​15 odds), 5-4 ( ​14 odds), 1-2 (all up to win) and 3-1 ( ​15 odds); total staked = £200

Note: 'All up to win' means there are insufficient participants in the event for place odds to be given (e.g. 4 or fewer runners in a horse race). The only 'place' therefore is first place, for which the win odds are given.

Returns (win fivefold) = £100 × (1/1 + 1) × (11/8 + 1) × (5/4 + 1) × (1/2 + 1) × (3/1 + 1) = £6412.50
Returns (place fivefold) = £100 × (1/4 + 1) × (11/40 + 1) × (5/16 + 1) × (1/2 + 1) × (3/5 + 1) = £502.03
Total returns = £6914.53

Full-cover bets[edit]

Trixie

E.g. £10 Trixie with winners at 4-7, 2-1 and 11-10; total staked = £40
Returns (3 doubles) = £10 × [(4/7 + 1) × (2/1 + 1) + (4/7 + 1) × (11/10 + 1) + (2/1 + 1) × (11/10 + 1)] = £143.14
Returns (1 treble) = £10 × (4/7 + 1) × (2/1 + 1) × (11/10 + 1) = £99.00
Total returns = £242.14

Yankee

E.g. £10 Yankee with winners at 1-3, 5-2, 6-4 and Evens; total staked = £110
Returns (6 doubles) = £10 × [(1/3 + 1) × (5/2 + 1) + (1/3 + 1) × (6/4 + 1) + (1/3 + 1) × (1/1 + 1) + (5/2 + 1) × (6/4 + 1) + (5/2 + 1) × (1/1 + 1) + (6/4 + 1) × (1/1 + 1)] = £314.16
Returns (4 trebles) = £10 × [(1/3 + 1) × (5/2 + 1) × (6/4 + 1) + (1/3 + 1) × (5/2 + 1) × (1/1 + 1) + (1/3 + 1) × (6/4 + 1) × (1/1 + 1) + (5/2 + 1) × (6/4 + 1) × (1/1 + 1)] = £451.66
Returns (1 fourfold) = £10 × (1/3 + 1) × (5/2 + 1) × (6/4 + 1) × (1/1 + 1) = £233.33
Total returns = £999.15

Trixie, Yankee, Canadian, Heinz, Super Heinz and Goliath form a family of bets known as full cover bets which have all possible multiples present. Examples of winning Trixie and Yankee bets have been shown above. The other named bets are calculated in a similar way by looking at all the possible combinations of selections in their multiples. Note: A Double may be thought of as a full cover bet with only two selections.

Should a selection in one of these bets not win, then the remaining winners are treated as being a wholly successful bet on the next 'family member' down. For example, only two winners out of three in a Trixie means the bet is settled as a double; only four winners out of five in a Canadian means it is settled as a Yankee; only five winners out of eight in a Goliath means it is settled as a Canadian. The place part of each-way bets is calculated separately using reduced place odds. Thus, an each-way Super Heinz on seven horses with three winners and a further two placed horses is settled as a win Trixie and a place Canadian. Virtually all bookmakers use computer software for ease, speed and accuracy of calculation for the settling of multiples bets.

Full cover bets with singles[edit]

Patent

E.g. £2 Patent with winners at 4-6, 2-1 and 11-4; total staked = £14

Fletcher Formula Roulette

Returns (3 singles) = £2 × [(4/6 + 1) + (2/1 + 1) + (11/4 + 1)] = £16.83
Returns (3 doubles) = £2 × [(4/6 + 1) × (2/1 + 1) + (4/6 + 1) × (11/4 + 1) + (2/1 + 1) × (11/4 + 1)] = £45.00
Returns (1 treble) = £2 × (4/6 + 1) × (2/1 + 1) × (11/4 + 1) = £37.50
Total returns = £99.33

Patent, Lucky 15, Lucky 31, Lucky 63 and higher Lucky bets form a family of bets known as full cover bets with singles which have all possible multiples present together with single bets on all selections. An examples of a winning Patent bet has been shown above. The other named bets are calculated in a similar way by looking at all the possible combinations of selections in their multiples and singles.

Should a selection in one of these bets not win, then the remaining winners are treated as being a wholly successful bet on the next 'family member' down. For example, only two winners out of three in a Patent means the bet is settled as a double and two singles; only three winners out of four in a Lucky 15 means it is settled as a Patent; only four winners out of six in a Lucky 63 means it is settled as a Lucky 15. The place part of each-way bets is calculated separately using reduced place odds. Thus, an each-way Lucky 63 on six horses with three winners and a further two placed horses is settled as a win Patent and a place Lucky 31.

Algebraic interpretation[edit]

Returns on any bet may be considered to be calculated as 'stake unit' × 'odds multiplier'. The overall 'odds multiplier' is a combined decimal odds value and is the result of all the individual bets that make up a full cover bet, including singles if needed. E.g. if a successful £10 Yankee returned £461.35 then the overall 'odds multiplier' (OM) is 46.135.

If a, b, c, d... represent the decimal odds, i.e. (fractional odds + 1), then an OM can be calculated algebraically by multiplying the expressions (a + 1), (b + 1), (c + 1)... etc. together in the required manner and subtracting 1. If required, (decimal odds + 1) may be replaced by (fractional odds + 2).[13][14]

Examples[edit]

3 selections with decimal odds a, b and c.Expanding (a + 1)(b + 1)(c + 1) algebraically gives abc + ab + ac + bc + a + b + c + 1. This is equivalent to the OM for a Patent (treble: abc; doubles: ab, ac and bc; singles: a, b and c) plus 1.Therefore to calculate the returns for a winning Patent it is just a case of multiplying (a + 1), (b + 1) and (c + 1) together and subtracting 1 to get the OM for the winning bet, i.e. OM = (a + 1)(b + 1)(c + 1) − 1. Now multiply by the unit stake to get the total return on the bet.[15][16]

E.g. The winning Patent described earlier can be more quickly and simply evaluated by the following:

Total returns = £2 × [(4/6 + 2) × (2/1 + 2) × (11/4 + 2) − 1] = £99.33

Ignoring any bonuses, a 50 pence each-way Lucky 63 (total stake £63) with 4 winners [2-1, 5-2, 7-2 (all ​15 odds a place) and 6-4 (​14 odds a place)] and a further placed horse [9-2 (​15 odds a place)] can be relatively easily calculated as follows:

Returns (win part) = 0.50 × [(2/1 + 2) × (5/2 + 2) × (7/2 + 2) × (6/4 + 2) − 1] = £172.75
or more simply as 0.50 × (4 × 4.5 × 5.5 × 3.5 − 1)
Returns (place part) = 0.50 × [(2/5 + 2) × (5/10 + 2) × (7/10 + 2) × (6/16 + 2) × (9/10 + 2) − 1] = £11.79
or more simply as 0.50 × (2.4 × 2.5 × 2.7 × 2.375 × 2.9 − 1)
Total returns = £184.54

For the family of full cover bets that do not include singles an adjustment to the calculation is made to leave just the doubles, trebles and accumulators. Thus, a previously described winning £10 Yankee with winners at 1-3, 5-2, 6-4 and Evens has returns calculated by:

£10 × [(1/3 + 2) × (5/2 + 2) × (6/4 + 2) × (1/1 + 2) − 1 − [(1/3 + 1) + (5/2 + 1) + (6/4 + 1) + (1/1 + 1)]] = £999.16

In effect, the bet has been calculated as a Lucky 15 minus the singles. Note that the total returns value of £999.16 is a penny higher than the previously calculated value as this quicker method only involves rounding the final answer, and not rounding at each individual step.

In algebraic terms the OM for the Yankee bet is given by:

OM = (a + 1)(b + 1)(c + 1)(d + 1) − 1 − (a + b + c + d)

In the days before software became available for use by bookmakers and those settling bets in Licensed Betting Offices (LBOs) this method was virtually de rigueur for saving time and avoiding the multiple repetitious calculations necessary in settling bets of the full cover type.

Settling other types of winning bets[edit]

Up and down

E.g. £20 Up and Down with winners at 7-2 and 15-8; total staked = £40
Returns (£20 single at 7-2 ATC £20 single at 15-8) = £20 × 7/2 + £20 × (15/8 + 1) = £127.50
Returns (£20 single at 15-8 ATC £20 single at 7-2) = £20 × 15/8 + £20 × (7/2 + 1) = £127.50
Total returns = £255.00
Note: This is the same as two £20 single bets at twice the odds; i.e. £20 singles at 7-1 and 15-4 and is the preferred manual way of calculating the bet.
E.g. £10 Up and Down with a winner at 5-1 and a loser; total staked = £20
Returns (£10 single at 5-1 ATC £10 single on 'loser') = £10 × 5/1 = £50
Note: This calculation of a bet where the stake is not returned is called 'receiving the odds to the stake' on the winner; in this case receiving the odds to £10 (on the 5-1 winner).

Round Robin

A Round Robin with 3 winners is calculated as a Trixie plus three Up and Down bets with 2 winners in each.

A Round Robin with 2 winners is calculated as a double plus one Up and Down bet with 2 winners plus two Up and Down bets with 1 winner in each.

A Round Robin with 1 winner is calculated as two Up and Down bets with one winner in each.

Flag and Super Flag bets may be calculated in a similar manner as above using the appropriate full cover bet (if sufficient winners) together with the required number of 2 winner- and 1 winner Up and Down bets.

Note: Expert bet settlers before the introduction of bet-settling software would have invariably used an algebraic-type method together with a simple calculator to determine the return on a bet (see below).

Algebraic interpretation[edit]

If a, b, c, d... represent the decimal odds, i.e. (fractional odds + 1), then an 'odds multiplier' OM can be calculated algebraically by multiplying the expressions (a + 1), (b + 1), (c + 1)... etc. together in the required manner and adding or subtracting additional components. If required, (decimal odds + 1) may be replaced by (fractional odds + 2).[13][14]

Examples[edit]

2 selections with decimal odds a and b in an Up and Down bet.
  • OM (2 winners) = (2a − 1) + (2b − 1) = 2(a + b − 1)
  • OM (1 winner) = a − 1
3 selections with decimal odds a, b and c in a Round Robin.
  • OM (3 winners) = (a + 1) × (b + 1) × (c + 1) − 1 − (a + b + c) + 2 × [(a + b − 1) + (a + c − 1) + (b + c − 1)] = (a + 1)(b + 1)(c + 1) + 3(a + b + c) − 7
  • OM (2 winners) = (a + 1) × (b + 1) − 1 − (a + b) + 2 × (a + b − 1) + (a − 1) + (b − 1) = (a + 1)(b + 1) + 2(a + b) − 5
    or more simply as OM = ab + 3(a + b) − 4
  • OM (1 winner) = 2 × (a − 1) = 2(a − 1)
4 selections with decimal odds a, b, c and d in a Flag.
  • OM (4 winners) = (a + 1) × (b + 1) × (c + 1) × (d + 1) − 1 − (a + b + c + d) + 2 × [(a + b − 1) + (a + c − 1) + (a + d − 1) + (b + c − 1) + (b + d − 1) + (c + d − 1)]
    = (a + 1)(b + 1)(c + 1)(d + 1) + 5(a + b + c + d) − 13
  • OM (3 winners) = (a + 1) × (b + 1) × (c + 1) − 1 − (a + b + c) + 2 × [(a + b − 1) + (a + c − 1) + (b + c − 1)] + (a − 1) + (b − 1) + (c − 1) = (a + 1)(b + 1)(c + 1) + 4(a + b + c) − 10
  • OM (2 winners) = (a + 1) × (b + 1) − 1 − (a + b) + 2 × (a + b − 1) + 2 × [(a − 1) + (b − 1)] = (a + 1)(b + 1) + 3(a + b) − 7
    or more simply as OM = ab + 4(a + b) − 6
  • OM (1 winner) = 3 × (a − 1) = 3(a − 1)

See also[edit]

Notes[edit]

  1. ^Sidney 1976, p.6
  2. ^Sidney 2003, p.13,36
  3. ^ abcdCortis, Dominic (2015). Expected Values and variance in bookmaker payouts: A Theoretical Approach towards setting limits on odds. Journal of Prediction Markets. 1. 9.
  4. ^Sidney 1976, p.96-104
  5. ^Sidney 2003, p.126-130
  6. ^Marek, Patrice (September 2018). 'Bookmakers' Efficiency in English Football Leagues'. Mathematical Methods in Economis - Conference Proceedings: 330–335.
  7. ^Sidney 1976, p.138-147
  8. ^Sidney 2003, p.163-177
  9. ^Sidney 1976, p.155-156
  10. ^Sidney 2003, p.170-171
  11. ^ abcSidney 1976, p.153-168
  12. ^ abcSidney 2003, p.169-177
  13. ^ abSidney 1976, p.166
  14. ^ abSidney 2003, p.169,176
  15. ^Sidney 1976, p.161
  16. ^Sidney 2003, p.176

References[edit]

  • Cortis, D. (2015). 'Expected Values and variance in bookmaker payouts: A Theoretical Approach towards setting limits on odds'. Journal of Prediction Markets. 1. 9.
  • Sidney, C (1976). The Art of Legging, Maxline International.
  • Sidney, C (2003). The Art of Legging: The History, Theory, and Practice of Bookmaking on the English Turf, 3rd edition, Rotex Publishing 2003, 224pp. ISBN978-1-872254-06-7. Definitive, and extensively revised and updated 3rd edition on the history, theory, practice and mathematics of bookmaking, plus the mathematics of off-course betting, bets and their computation and liability control.

Further reading[edit]

  • 'Finding an Edge', Ron Loftus, US-SC-North Charleston: Create Space., 2011, 144pp.
  • 'How to make a book', Phil Bull, London: Morrison & Gibb Ltd., 1948, 160pp.
  • 'The book on bookmaking', Ferde Rombola, California: Romford Press, 1984, 147pp. ISBN978-0-935536-37-9.
  • The Art of Bookmaking, Malcolm Boyle, High Stakes Publishing 2006.
  • Secrets of Successful Betting, Michael Adams, Raceform, 2002.
  • The Mathematics of Games and Gambling, Edward W. Packel, Mathematical Association of America, 2006.
  • The Mathematics of Gambling, Edward O. Thorp, L. Stuart, 1984.
  • 'Maximin Hedges', Jean-Claude Derderian, Mathematics Magazine, volume 51, number 3. (May, 1978), pages 188–192.
  • 'Carnap and de Finetti on Bets and the Probability of Singular Events: The Dutch Book Argument Reconsidered' Klaus Heilig, The British Journal for the Philosophy of Science, volume 29, number 4. (December, 1978), pages 325–346.
  • 'Tests of the Efficiency of Racetrack Betting Using Bookmaker Odds', Ron Bird, Michael McCrae, Management Science, volume 33, number 12 (December, 1987), pages 152–156.
  • 'Why is There a Favourite-Longshot Bias in British Racetrack Betting Markets', Leighton Vaughan Williams, David Paton. The Economic Journal, volume 107, number 440 (January, 1997), pages 150–158.
  • Optimal Determination of Bookmakers' Betting Odds: Theory and Tests, by John Fingleton and Patrick Waldron, Trinity Economic Paper Series, Technical Paper No. 96/9, Trinity College, University of Dublin, 1999.
  • 'Odds That Don't Add Up!', Mike Fletcher, Teaching Mathematics and its Applications, 1994, volume 13, number 4, pages 145–147.
  • 'Information, Prices and Efficiency in a Fixed-Odds Betting Market', Peter F. Pope, David A. Peel, Economica, New Series, volume 56, number 223, (August, 1989), pages 323–341.
  • 'A Mathematical Perspective on Gambling', Molly Maxwell, MIT Undergraduate Journal of Mathematics, volume 1, (1999), pages 123–132.
  • 'Probability Guide to Gambling: The Mathematics of dice, slots, roulette, baccarat, blackjack, poker, lottery and sport bets', Catalin Barboianu, Infarom, 2006, 316pp. ISBN973-87520-3-5.

External links[edit]

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What is the value of the blackjack system called 'Mastering the Flow?' It's marketed via an infomercial, and the website is www.changetheodds.com. It claims not to be a counting system, yet the vague description of the system that the website gives makes it sound like counting to me. The claims are pretty out-there: 'Win every time' etc. I count cards (using the KO PREFERRED), and understand that this new 'system' has to be either a simplistic count strategy, or a scam. Would you look into it for us, the gullible public?

I had a look at the web site and also found what little he says about the theory behind his system makes it sound like card counting. However I'm deeply skeptical of anything that claims to 'blow old fashioned card counting away.' I think we can file this under 'If it sounds too good to be true is probably is.'
Update: The web site in question vanished sometime after the publication of this question.

Any tips on money management in blackjack? I usually double after a win, go back to my original bet after three wins (or any loss), and play the game according to the book. I usually do pretty well, but it's slow and steady and not very exciting. Any tips?

I don't put a lot of emphasis on betting systems. In the long run you will lose the same percentage of money bet no matter what system you use. So my advice is use a system that maximizes the fun of the game.

In blackjack, do you improve your chances by playing two hands at once for x each, versus 1 hand at a time for 2x? If the odds are better, how much better?

The simple answer is no, it neither helps you nor hurts you. However, you will have less bankroll variance by betting two hands of x as opposed to one of 2x. Card counters are an exception to the simple no, they may play multiple hands to draw more cards out of a deck rich in good cards, thus improving their odds.

Love your site. I've even taken your blackjack data and made it into a full-color pocket-sized page that I carry in my briefcase for those unexpected trips to Vegas. I've memorized and follow your rules and generally do well (but of course there are times when I lose.) Two questions, you said in a previous answer that you don't cap your winnings. How do you determine when to stop? When have you 'won enough' so you avoid regression toward the mean and lose it back?
Second question, does the number of hits one takes effect the outcome? For example, if I have five cards that total 15 against a dealer's 10, am I pressing my luck by taking a sixth card? In other words, are the odds of busting on a 5-card 15 the same as busting on a 2-card 15?

Thank for the compliment and I'm happy to help your bankroll last longer. When I gamble for fun I keep playing until it isn't fun any longer. Usually the fun ends when I have lost too much or have played too long. With the ups and downs of blackjack it takes hundreds of hours before regression toward the mean will cause actual results to look like expected results. Furthermore, the player who puts a conservative cap on their winnings is never going to experience the fun of a long hot winning streak. Keep in mind this is just what works for me. You should do what you are comfortable with. Everything I have to say about money management can be summarized by the following two rules (1) don't gamble with money you can't afford to lose, and (2) don't gamble if it isn't fun.
Regarding your second question, there is something to be said about the composition of a hand. The fewer the decks the more this is true. My blackjack appendix 3A and appendix 3B show the exceptions to single- and double-deck blackjack, based on the composition of the hand. These appendices show that the more cards that are in your hand the more inclined you should be to stand. Regarding your 15 against a 10 example, there are two situations in single deck blackjack where you should stand when the 15 is composed of 5 cards, A+A+A+6+6 and A+A+3+5+5. Note that in both of these situations either two fives or two sixes have left the deck which are the two most helpful cards for the player. The two situations where you should be the most inclined to stand if you have a multiple card hand are 16 against a 10 and a 12 against a 3.

Do you mean to tell me that man has designed a way to put three million transistors on a single chip (microprocessor) the size of a finger nail, and we don't have a way to beat a 50/50 even money game bet. I find that to be unbelievable, besides I found that computer simulations are definitely not the same as live world action. Also why don't casinos introduce video blackjack to thwart the card counters and get rid of dealers?

I have said numerous times that there is no long-term way to beat a game with a house edge. If there were a true 50/50 game with no house edge it would be impossible to guarantee beating or losing to it under real world conditions. The results always approach the house edge in the long-term. It is not just computer simulations that back this up but the fundamental laws of probability.
About video blackjack, that may be the way of the future. I have seen fully electronic tables with video display at the World Gaming Expo. I have also seen tables that with cameras can track every bet and every play each player makes. This enables the house to accurately comp players and alert them to card counters. These tables look and feel like any other blackjack table, so you card counters may be out of business if these tables are successful.

Have you ever heard of the Ken Fuchs progression. If so, would you please e-mail me or post the details on your site.

I’m not familiar with it. Ken Fuchs co-wrote Knock-Out Blackjack so he can’t be all bad. However I just hear the word progression and I’m immediately skeptical.

I’ve got a question about 'progressive betting' (e.g. 'Another Experiment', Player 2 on your Betting Strategies page). Obviously in normal bj play you experience streaks of wins and loses. Where is the faulty logic in 'minimize your losing streaks by resetting at 1 unit, and increase your winning streaks by raising 1 unit after each win?' FYI, I actually play a little variation of that: 15, 30, 45, 50, 75, 100, 125, etc...Thanks for you time. And, please don’t try to humiliate me like Ann {what’s-her-name} on The Weakest Link :-) I really love your site!!! Thanks for all of the great info.
Fletcher formula blackjack pdf

Progressive betting systems, like yours, will turn a good session into a great one without the risk of catastrophic loss as with regressive systems like the Martingale. However progressive systems will turn a choppy neutral session into a bad one. Consider what would happen if you alternated between a win and a loss the entire session. The wins would all be at $15 and the losses at $30. Funny you should mention the ’Weakest Link.’ I tried out for that show during the summer and didn’t make it. It is probably just as well because I’m not that witty in real life and doubt I could come up with a good rejoinder to one of Ann’s jabs.

I play the negative system in black jack meaning I double every time I lose until I Win. I wanted to what the odds are of losing 4,5,6,7,8,9 hands in a row? How many hands should I expect to play till I lost 8 hands which is my stopping point?

The name for this system is the Martingale. Ignoring ties the probability of a new loss for a hand of blackjack is 52.51%. So the probability of losing 8 in a row is .52518 = 1 in 173.

Formula
Can You tell me the expected return in Black Jack if a player wagers all his money in one hand and not having money for split’s or double’s. Thank You.

If you can’t double or split that adds 1.9% to whatever the house edge is otherwise. This just goes to show that you should always have double or split money available if you need it.

I’ve been playing blackjack for quite awhile using basic strategy, mostly betting an even unit each hand. Occasionally I will increase the bet because I 'feel' like I am going to win the next one. I would think that just about all recreational players bet on feel once in a while at least. I was reading through some of your past Ask the Wizard columns and saw your calculation of the probability of a string of losses in the August 4, 2002 Column. You know those emotional thoughts that pop in head while gambling (well maybe not your head), 'I’m due for a win!'

That column seemed to put the mathematics to that 'feeling' a player can get. In that columns’ example of a player losing 8 consecutive hands of blackjack the odds were (.5251^8 or about 1 in 173). My question though is what does that really mean? Is it that when I sit down at the table, 1 out of my next 173 playing sessions I can expect to have an 8 hand losing streak? Or does it mean that on any given loss it is a 1 in 173 chance that it was the first of 8 losses coming my way?

I know, I know, its some sort of divine intervention betting system I am talking about and no betting system affects the house edge. I’m still curious though. Besides every once in awhile throwing down a bigger bet just adds to the excitement and for some reason it seems logical that if you have lost a string of hands you are 'due' for a win.

I have no problem with increasing your bet when you get a lucky feeling. What is important is that you play your cards right. Unless you are counting cards you have the free will to bet as much as you want. As I always say all betting systems are equally worthless so flying by the seat of your pants is just as good as flat betting over the long term. When I said the probability of losing 8 hands in a row is 1 in 173 I meant that starting with the next hand the probability of losing 8 in a row is 1 in 173. The chances of 8 losses in a row over a session are greater the longer the session. I hope this answers your question.

First let me say I love your site and will be visiting each of the advertisers to help support it. I hope you are doing very well financially as you are undoubtedly saving a lot of people a lot of money. It is amazing what I see in the casinos and will recommend your site to anyone who will listen (most losers won’t, I get a lot of heat when I hit a 12 vs a dealer 2 even when I explain the math). My question is do you have any advice for Blackjack players participating in Blackjack tournaments? I have participated in a few and have came very close to advancing to the 'money' round with no real strategy other than stay close to the leaders on the table and bet it all on the last hand. Any advice would be greatly appreciated!

Thanks for the kind words. I appreciate the thought of visiting the advertisers. However the casinos don’t care about click throughs as much as they used to and now what matters is new real money players, and how profitable those players are. So unless you might actually play there is no pressure any longer to click through the banners.

Blackjack tournaments are not my strong subject. For advice on that I would highly recommend Casino Tournament Strategy by Stanford Wong. Wong says that if you are behind to bet opposite of the leader, small when he bets big, and big when he bets small. If you are in the lead then you should bet with the second highest player. The book gets into much more detail. Speaking of supporting my site, it helps to click through my Amazon links when buying books there.

How do you calculate the expected return for a blackjack game with a .5% house edge and a 20x play requirement and an initial Bank Roll including bonus of $1000. Does it matter if you flat bet (assuming that the bets are relatively small compared to the BR) or bet based on the Kelly criterion, or does the Kelly criterion just affect the risk of ruin?

Your expected loss of this play is 0.005*20*$1000=$100. The betting system will not affect the expected loss, but will affect the volatility.

Does losing a hand at blackjack increase the probability that the composition of the deck is in your favor? More specifically, is your expected return on one hand ever positive after a given net loss since the last shuffle?

Without knowing anything else, if you lost the last hand in blackjack then it is slightly more likely that more small cards than large just left the deck. This would make the remaining deck more large card rich and thus lower the house edge. However I speculate this is an extremely small effect. Yet it does go to show that if you must use a betting system one that increases the bet after a loss is better than one that increases after a win. I hesitate to put this in writing at all because again the effect is probably very small and I fear system sellers will misquote me and imply I endorse any system, which I DO NOT.

I have a question about a blackjack tournament, where only the largest stack at the end is paid. Assume 1000 players start with 100$ in chips and can bet 5 hands at a time, from 1-10$ per hand. If no one knows anything about the other chipstacks, what chipstack should you be looking for before being satisfied?

You didn’t say how many rounds there were. However, I would bet $10 in all five hands every hand, or go bust trying. With 1,000 players and a relatively low max bet you’ll need all the variance you can get.

As a blackjack player, I recognize betting systems don’t work in the long run. However, having played a lot of blackjack, streaks (good and bad) do happen. So, I am wondering, without card counting, would tracking simple wins vs. losses, compared with the remaining cards in a 6 or 8-deck shoe, deck be meaningful? In other words, would you be able to obtain a small percentage advantage for the remaining third of the shoe if you knew the win-loss ratio was out of whack?

I’ve been wondering this myself for years. In 2004 somebody accepted my betting system challenge, claiming he could beat blackjack without counting. The details are in my page on the Daniel Rainsong challenge. After I posted it, I received a message from a blackjack genius, who goes by the handle 'Cacarulo.' He challenged me under the same conditions and blackjack rules set forth in the Rainsong challenge.

Knowing how knowledgeable he is about blackjack, I felt that he was probably right, so I declined the challenge. I asked anyway how he would have gone about his strategy, but he wouldn’t tell me. I tend to think that he would have bet the minimum most of the time, except if it was late in the shoe, and the ratio of losses to wins was very high since the last shuffle, he would have bet the maximum. The reason is that losing is positively correlated to small cards being played, and winning to large cards. In other words, a benefit of losing is that it tends to make the count better. However, this is a weak correlation. My challenge allowed the player a bet range of 1 to 1,000, which is probably enough to overcome the house edge, but it will be hard to find a real casino okay with a jump in bet size by a factor of 1,000.

The short answer to your question is, no, tracking wins and losses will not help enough to warrant the bother of doing it.