# Thread: Grand Martingale Strategy with Stop Loss

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## Grand Martingale Strategy with Stop Loss

Can someone help me understand why my math doesn't work with this strategy?
Using basic blackjack strategy, bets would follow a grand martingale (1, 3, 7, 15, 31), except that if the bet of 31 is lost, the betting starts over at 1. Now based on googling, there is a 2.8% chance of losing 5 hands in a row or a 2.8% chance of losing the bet of 31. That would mean 97.2% of the time, I would win 1. The expected value of this is about .1 profit per hand and assuming a large enough bankroll, will this not be profitable in the long term? What am I missing? I tested this on a few online sites and have profited quite a bit.

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Originally Posted by Dummy
Can someone help me understand why my math doesn't work with this strategy?
Using basic blackjack strategy, bets would follow a grand martingale (1, 3, 7, 15, 31), except that if the bet of 31 is lost, the betting starts over at 1. Now based on googling, there is a 2.8% chance of losing 5 hands in a row or a 2.8% chance of losing the bet of 31. That would mean 97.2% of the time, I would win 1. The expected value of this is about .1 profit per hand and assuming a large enough bankroll, will this not be profitable in the long term? What am I missing? I tested this on a few online sites and have profited quite a bit.
You likely win for a while and then eventually you hit a long streak that will wipe you out. You can't win in the long run with this strategy.

You are picking up pennies in front of a steamroller.

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I think you have a great strategy. You should do it for real. Please report back.

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Originally Posted by Dummy
Can someone help me understand why my math doesn't work with this strategy?
Using basic blackjack strategy, bets would follow a grand martingale (1, 3, 7, 15, 31), except that if the bet of 31 is lost, the betting starts over at 1. Now based on googling, there is a 2.8% chance of losing 5 hands in a row or a 2.8% chance of losing the bet of 31. That would mean 97.2% of the time, I would win 1. The expected value of this is about .1 profit per hand and assuming a large enough bankroll, will this not be profitable in the long term? What am I missing? I tested this on a few online sites and have profited quite a bit.
Dummy,

When you lose five in a row, you don't lose just 31 on the streak: you actually lose 1 + 3 + 7 + 15 + 31 = 57.

Let's try the math this way. For typical BJ rules, Basic Strategy gives an EV of about -0.5%, or -0.005 (give or take a bit due to house rules). This means that when you place a 1-unit bet, on average you'll lose 0.005 units. Similarly, when you place a bet "b" of 3, 7, 15, or 31 units, on average you'll lose 0.005*b. This means that, on average, no matter how much or little you bet, you'll lose 0.005 times whatever you wagered.

Hope this helps!

Dog Hand

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You will not have big enough bankroll. Also the casino won’t have an “unlimited” maximum for you to keep chasing.

5, 15, 35, 75, 155, 315, 635, 1275, 2555, 5115
Total 10180

That’s not counting double down and/or splits.

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This reminds me of one of my first collisions with gambling/statistical theory.

I don't remember exactly how old I was when I read "Scarne's Complete Guide To Gambling." I feel like I was about 11, maybe that I took it out of the library but then bought my own copy with some of my Bar Mitzvah money, so of course I was 13 then. ("Today I am a fountain pen.") But I also remember feeling the need to prove that the Martingale (and Great Martingale) couldn't work, and I don't think I had my first serious encounter with computers until I was 14.

But I know I wrote a BASIC program to play one or both "strategies" (don't most "strategies" have at least SOME possibility of winning under favorable conditions?) and used a craps model, win chances of 244/495. And just for giggles I totaled the bets and net loss. Surprise! the player lost 1.4% of the amount he bet.

I verified a lot of Scarne's calculations because that's what 13-year-old math nerds do.

I actually had a player tonight who was playing a Martingale, but his bankroll was hugely short. He played two hands at 10/20/40/80, and when the 80's lost, well I think his starting bankroll was only around \$450, so he was S.O.L. by that point.

I know I'm wandering all over the place here, but since I retired I've had two extended gigs, one driving Uber from 2015-2017 and now dealing in an out-of-the-way casino. What they have in common is that you get a huge cross-section of humanity.

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There may be something wrong here.

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a,The Martingale Strategy focus on losing and getting back to zero. You lose 3 bets and bet 9 units to get back to zero. But it ignores any betting action above zero. Like, once you win several bets.
b, D.S. mentioned it years ago, "you'll never overcome the house edge which is present on every bet."
c, these yellow pages are my favorite part of the forum.

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