Roulette maths · Maths problem · 10 minute

Problem: di table limit

A $10 Martingale at a $500 table. Ow often it bruk, ow much it lose wen it bruk, an it help if di limit go up?

Short ansa

Six loss inna a row bruk it: 1.8% evry cycle, bout 60% a 100-spin session. Di bruk cost $630. If di limit go up to $5,000, di bruk come more rare (0.25% evry cycle) an bigga ($5,110). Di expected loss fi evry dolla yuh bet a 2.70% at any limit.

base / limit
$10 / $500
loss fi bruk it
6
p(bruk) evry cycle
1.8%
loss wen it bruk
$630

Di problem

A playa bet $10 pon redbet demRedEven-money bet pon di 18 red numba. Inna French: rouge.Read di whole ting → an double afta evry loss, an go back to di start afta a win. Di table maximum a $500. (a) Ow much loss inna a row bruk di progressionstrategy demProgressionAny rule weh change di stake based pon di result dem weh pass. Negative progression raise it afta loss, positive progression afta win.Read di whole ting →? (b) Wah a di probabilitymathsProbabilityDi chance fi a result, fram 0 to 1 or 0% to 100%. One numba: 1/37 = 2.70%.Read di whole ting → evry cycle? (c) Wah yuh lose wen it bruk? (d) Ow a $5,000 limit change di ansa dem? (e) Any limit mek di system profitable?

Di table limit dem inna roulette

Solution (a)–(c)

Stake dem: 10, 20, 40, 80, 160, 320. Di sevent one woulda be 640 > 500, suh six loss bruk it. (b) p(loss) = 19/37 pon red; (19/37)⁶ = 0.0183, bout 1.8% evry cycle. A cycle last bout two spin pon average, suh a 100-spin session have roughly 50 cycle an p(at least one bruk) ≈ 1 − 0.9817⁵⁰ ≈ 60%. (c) 10 + 20 + 40 + 80 + 160 + 320 = $630, weh a 63 base unitmoney mattaUnitDi base stake weh a system or a playa work wid. Dem describe progression inna unit suh dem work at any table.Read di whole ting →, gainst di $10 di cycle did a try fi win.

limitloss fi bruk itp(bruk) evry cycleloss wen it brukp(bruk inna 100 spin)win yuh need fi get it back
$10046.95%$150≈ 97%15
$50061.8%$630≈ 60%63
$1,00070.94%$1,270≈ 38%127
$2,00080.48%$2,550≈ 22%255
$5,00090.25%$5,110≈ 11%511
$20,000110.07%$20,470≈ 3%2,047
Evry time di ceilin double, di bruk come bout half as likely an two time as expensive. Di product hardly change.

Solution (d)

At $5,000: stake up to 2,560 allow; di tent stake, 5,120, get refuse. Nine loss bruk it: (19/37)⁹ ≈ 0.25% evry cycle, bout 11% a 100-spin session. Loss wen it bruk: 10 + 20 + … + 2,560 = $5,110. Di playa buy a catastrophe weh come more rare fi di price a one weh bigga. Ova nuff session di expected cost a di bruk dem a p × loss ≈ 0.0183 × 630 = $11.5 evry cycle at di $500 limit an 0.0025 × 5,110 = $12.8 at $5,000; di two a dem close but nuh equal, an each one a di expected lossmathsExpected lossExpected value times all di money yuh bet; di average amount yuh lose ova a session or a period (di loss yuh fi expec pon average).Read di whole ting → a di cycle plus di $10 weh di cycle dem weh win earn.

Solution (e)

No. Expected loss evry cycle = (expected total stake inna di cycle) / 37, at any limit, cause evry bet a −1/37 a itself. Di limit only decide ow di loss share out between nuff small win an a few big loss. Wid nuh limit an a bankrollmoney mattaBankrollAll di money yuh set aside fi play. Fi manage yuh bankroll mean yuh decide ow much a it yuh a go risk pon evry bet an evry session.Read di whole ting → weh nuh have nuh end, di progression woulda “work”, inna di sense seh it woulda neva bruk, an it woulda also bet a amount weh nuh have nuh end wid expected loss a 2.70% a dat endless amount. Di table limitpon di tableTable limitDi minimum an maximum bet dem allow. Di maximum a weh stop progression weh double up.Read di whole ting → nuh a wah stop Martingalestrategy demMartingaleProgression weh double di bet afta evry loss. Look inna di Strategy section fi see wah it do an wah it nuh do.Read di whole ting → fram work. A di arithmetic.

Martingale at $10 base, 100 spin: mean result by limit (simulate)$
$500 limit
≈ −$75
$1,000 limit
≈ −$75
$2,000 limit
≈ −$72
$5,000 limit
≈ −$70
flat $10, any limit
$27
$
04080
Di bar dem show di size a di loss. If di limit go up, di mean hardly move; di progression bet bout $2,800 evry 100 spin, nuh matta wah di ceilin be.

Two real table

Thorp example a one $1 table wid a $1,000 maximum, weh a playa a hope fi win $30 fi dinna one dolla at a time. Di stake dem 1, 2, 4 … 512 allow ten bet, suh ten loss inna a row bruk di progression: one time inna 785 cycle pon a European wheel (one time inna 613 pon a American one), an it cost $1,023. Thirty cycle all come good 96.2% a di time. Di odda 3.8% lose bout $1,000, an di average result a di evenin a −$9.17, weh a exactly 1/37 a di $339 di thirty cycle stake pon average. A $5 table wid a $2,000 maximum nuh different: stake up to $1,280 allow nine bet, an di bruk come one time inna 403 cycle pon a European wheel (one time inna 323 pon a American one) an cost $2,555.

Double stake a climb up to di table maximum while dinna a wait inna di nex room.

A rich playa

Give di progression a deep bankroll instead a a low limit: 1,000 unit, a one-unit base an 1,000 spin pon red, an start again at one unit wenever di nex double more dan wah lef. Wi simulate a million evenin like dat. Pon a European wheel 52% finish ahead, 21% lose evryting, an di average result a −124 unit. Even inna a game wid nuh zeropon di wheelZeroDi one green pocket weh no even-money, dozen or column bet nuh cover; a weh di house edge come fram. Nex name: single zero, 0.Read di whole ting →, weh evry bet fair, only bout 60% woulda finish ahead. Di usual evenin a a small win; di average get pay fah by di evenin dem weh end at zero.

wheelfinish wid profitlose di 1,000 unitaverage result
nuh zero (a fair game)60%15%0
European52%21%−124 unit
American45%30%−250 unit
Fi wi simulation, a million evenin fi evry wheel. Di average dem a 1/37 an 1/19 a wah di progression stake inna 1,000 spin: bout 4,600 unit pon a European wheel an 4,750 pon a American one.

Di lesson

Casino set limit fi cap dem own variancemathsVarianceA measure a ow wide di result dem spread roun di expected value. High fi straight up, low fi even-money bet.Read di whole ting →, nuh fi beat system. Fi beat Martingale a sumting extra weh dem glad fi get, an di arithmetic woulda beat it anyway. A playa weh tink seh di limit a di problem find di cliff an tek it fi di slope.

Formula

p(bruk) = (19/37)ᵏ, k = loss weh di limit allow
loss wen it bruk = base · (2ᵏ − 1)
E[loss evry cycle] = E[stake inna cycle] / 37

Question dem

A bigga bankroll woulda fix it?

It mek yuh survive to a higha limit, weh di bruk more rare an bigga. Di expected loss fi evry dolla nuh change.

Wah bout a “grand Martingale” weh add a unit pon evry double?

Stake dem 10, 30, 70, 150, 310: yuh hit di $500 limit afta five loss, an di bruk cost $570. Same 2.70%.

Wah mek casino have a maximum at all?

Suh dat one playa cyaan bet more dan wah di casino reserve can pay easy. Variance management.

Fun wid maths

Try dem yuhself fus. Evry ansa fold up; open it wen yuh ready.

  1. A Martingalestrategy demMartingaleProgression weh double di bet afta evry loss. Look inna di Strategy section fi see wah it do an wah it nuh do.Read di whole ting → start at $100 pon redbet demRedEven-money bet pon di 18 red numba. Inna French: rouge.Read di whole ting → an allow itself at most n bet a cycle: afta n loss inna a row it give up an start ova. Write di average result a one cycle as a formula inna n, an work it out fi 5, 6 an 7 bet pon a European wheel.

    Show di ansa

    Ansa Di average a 100 × (1 − (38/37)ⁿ): −$14.26 fi 5 bet, −$17.35 fi 6 an −$20.52 fi 7. Fi allow more bet mek di average cycle worse, not betta.

    A cycle win $100 unless all n bet lose, an dat happen wid chance qⁿ, weh q = 19/37. Wen dem all lose, di stake dem 100, 200 … 100 × 2ⁿ⁻¹ add up to 100 × (2ⁿ − 1). Suh di average a 100 × (1 − qⁿ) − 100 × (2ⁿ − 1) × qⁿ = 100 × (1 − (2q)ⁿ).

    Yah so 2q = 38/37, a likkle more dan 1, suh (2q)ⁿ grow wid n an di average drop: n = 5 give 1.1426 an −$14.26; n = 6 give 1.1735 an −$17.35; n = 7 give 1.2052 an −$20.52. A longa ladda lose less often, inna 3.6%, 1.8% an 0.9% a cycle, but each loss twice as big, an more money cross di table each cycle, at 2.70% a evry bet.

    Pon a American wheel 2q = 40/38 an di figure dem a −$29.24, −$36.04 an −$43.20 (Taylor, 2021). Inna a game wid no zeropon di wheelZeroDi one green pocket weh no even-money, dozen or column bet nuh cover; a weh di house edge come fram. Nex name: single zero, 0.Read di whole ting → 2q = 1, an evry cycle average exactly zero no matta ow long di ladda.

  2. Di “grand Martingale” double di stake afta a loss an add one unitmoney mattaUnitDi base stake weh a system or a playa work wid. Dem describe progression inna unit suh dem work at any table.Read di whole ting →, suh di stake dem run 1, 3, 7, 15, 31 … Ow much yuh up wen di fus win come pon di 1st, 2nd, 3rd or kth bet? At a $10 unit an a $500 maximum, ow often a cycle bruk, an wah a cycle cost pon average?

    Show di ansa

    Ansa A win pon di kth bet lef yuh k unit up: +1, +2, +3 an suh on. At $10 an $500 di cycle bruk afta five loss, 3.57% a cycle, fi −$570. Pon average a cycle lose $2.32 outta $85.73 weh yuh stake: 2.70%.

    Di kth stake a 2ᵏ − 1 unit: 1, 3, 7, 15, 31. Di fus k − 1 stake add up to 2ᵏ − 2 − (k − 1) = 2ᵏ − k − 1. A win pon di kth bet pay 2ᵏ − 1, suh di cycle end (2ᵏ − 1) − (2ᵏ − k − 1) = k unit up: one extra unit fi evry loss bifo di win.

    At $10 a unit di stake dem a $10, $30, $70, $150 an $310; di nex one, $630, deh ova di $500 maximum. Five loss inna a row, (19/37)⁵ = 3.57%, cost 10 + 30 + 70 + 150 + 310 = $570.

    Average: di win dem bring in $10 × k wid chance (19/37)ᵏ⁻¹ × 18/37 fi k = 1 to 5, an di bruk tek $570 wid chance 3.57%; togedda −$2.32. Di money weh yuh stake average $85.73 a cycle, an 2.32/85.73 = 2.70%. Di regular Martingale at di same table bruk afta six loss, 1.83% a cycle, fi −$630, an lose $1.74 outta $64.20 weh yuh stake: 2.70% again.

  3. A playa plan a Martingale pon red wid a $1 fus bet at a table weh di limit a $1,000, suh ten bet possible: $1, $2, $4 an suh on up to $512. Ow often a cycle lose all ten, ow long dat tek pon average, an ow often a evenin a 200 bet end dat way?

    Show di ansa

    Ansa A cycle lose all ten bout one time outta 784, an dat cost $1,023. Dat a bout 1,600 bet pon average, an a evenin a 200 bet lick di wall bout 11% a di time. A cycle still lose $0.31 pon average outta $11.31 weh yuh stake: 2.70%.

    A bet pon red lose wid chance 19/37, di zero include. Ten inna a row: (19/37)¹⁰ ≈ 0.00128, bout 1 outta 784. Di stake dem 1 + 2 + 4 + … + 512 add up to $1,023.

    A cycle tek 2.05 bet pon average, suh 784 cycle tek bout 1,600 bet. If yuh count spin by spin, a run a ten loss turn up somewhere inna 200 bet 11.3% a di time.

    Between disasta dem di playa win $1 a cycle: bout $783 bifo di bad one, den −$1,023, bout −$240 ova di whole stretch. Pon each cycle: 1 × (1 − 0.00128) − 1,023 × 0.00128 ≈ −$0.31. Money weh yuh stake pon each cycle: 1 + 2 × (19/37) + 4 × (19/37)² + … + 512 × (19/37)⁹ ≈ $11.31. An −0.31/11.31 = −2.70%.

    Compare a $10 fus bet at a $500 limit, six bet: di wall come one time outta 55 cycle, an a evenin a 200 bet meet it 84% a di time. A higha limit mek di crash more rare an bigga, not cheaper.

Sumting fi laugh

More rare an bigga, at evry limit. Di product nuh change.

More rare an bigga, at evry limit. Di product nuh change.

Source dem

  1. Ethier, S. N. The Doctrine of Chances: Probabilistic Aspects of Gambling. Springer, 2010. Chapta 13, roulette.
  2. Thorp, E. O. “Optimal gambling systems for favorable games.” Review of the International Statistical Institute 37(3), 1969.
  3. Thorp, E. O. The Mathematics of Gambling. Gambling Times / Lyle Stuart, 1984.
  4. Epstein, R. A. The Theory of Gambling and Statistical Logic, 2nd ed. Academic Press, 2013.
wi check it 2026-09-28model: European wheel, single zeroow wi work it out ↗source dem ↗