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Anonymous asked in Games & RecreationGambling · 1 decade ago

Roulette probability question?

What is the probability of winning at roulette if you bet on the same color and double your bet each time you loose till you win? Is this an almost guaranteed way to win at this game?

Let's say you bet $20 on red. You have a 50/50 chance at winning or loosing. Let's say you loose so you bet $40 the next time and loose again. you bet $80 the third time. The odds are in your favor that eventually you will win if you keep doubling your money. Is this a good way to beat the game?

11 Answers

  • ZCT
    Lv 7
    1 decade ago
    Favorite Answer

    The game has been around for about 200 years. If there were any sure fire way to beat the game, the casino would have changed the rules years ago.

    The system you are describing is known as the martingale system.

    You bet $20, $40, $80, $160, $320, $640, $1280 etc. Doubling each time you lose until you win your money back.

    Of course the first problem is that the odds of winning are not 50/50 as you stated. You are forgetting that there is a zero and double zero. These green numbers mean that you lose your bet 20/38 times. You only win 18/38 times. This subtle change to the odds means that the house gains an edge of 5.26%.

    The next problem is that if you lose six times in a row you are out $1,260 and need to bet $1,280 for just less than a 50/50 shot at winning your money back. Of course if you lose again, you are now out two and a half grand.

    While it is unlikely that you will lose six times in a row, it can and does happen. And when it does, you are going to be kicking yourself.

    The final minor problem with your idea is that there is usually an upper limit on most tables. So you start off with a $20 bet, and a few double downs later, you hit the table max. Now you have to go to the high stakes area and find a table offering you the chance to bet a couple of grand on a single spin. If you win, and want to go back to low stakes betting, it's time to walk all the way back to the original table and start again.

    Frankly it is a long and tedious way to win a small amount or go broke. Most people would not have the discipline or patience to sit there for hours trying to work this doomed system. Before long they would deviate from the system and start betting other stuff.

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  • 1 decade ago

    First off, betting on red or black is not a 50/50 bet. The wheel has a green "0" (European) and the American wheel adds a "00" to the mix. These give the house an advantage when you bet on red or black. (The casino wouldn't make money in the long run if they offered a 50/50 wager.)

    The system you mention will give you many small wins, and a few big losses. The losses will, in the long run, total more than the wins. As hard is it is to believe, you will at some point lose enough bets that the house limits will not allow you to make a large enough bet to recoup your losses.

    American roulette has a 5.26% house edge. European roulette is about half of that. Either way, there is no betting system that can reduce the house edge.

    Many people try, I see it all the time. As a casino employee, I love the players who use these systems. They are guaranteed money in the bank.

    Source(s): over 13 years casino experience
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  • ?
    Lv 5
    1 decade ago

    First up you don't have a 50/50 chance to win. The odds are 20/18 against winning at the American (double zero) wheel and 19/18 at the European wheel.

    Here's the sequence:

    20, 40, 80, 160, 320, 640, 1280, 2560, 5120, 10240, 20480, 40960, 81920 (and so on)

    After ten losers you are already $20000 in the hole and you have to bet more than $20000 on the next spin.

    Can you afford that much?

    It doesn't matter because the casino has a maximum limit and will not accept bets above that limit.

    In my local casino, the limit is $5000, so I'm out of action after eight consecutive losers.

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  • 4 years ago

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  • 1 decade ago

    First - There is no guaranteed way to win ANY game of chance (anyone trying to tell you otherwise is just blowing smoke up your exhaust pipe).

    Second - Roulette is a game of chance.

    Mo's answer is actually quite complete. Another way to look at it is that after you loose your first bet (say $20) you are risking $40, then $80, $160, $320, $640, $1280, etc. just to be $20 ahead. As Mo (paraphrasingly) said, betting in geometrically increasing rates to break even is the fastest way to go broke (and after the fourth or 5th increase, that first $20 bet is pretty insignificant). Except for perhaps ESP, there are no skills that can change the probabilities.

    If you enjoy games like this, try an opposite tact - your odds of winning will be lower, but you risk much less money: take a limited amount of money with you (say $1000) for your roulette bankroll. Then, on your first bet and any bet after you have lost the previous bet, bet your minimum. IOW, if you take $1000, that means that you have 50 $20 bets, 100 $10 bets, etc. Then, any time you win just bet your previous payoff (previous bet plus winnings). If you do this, at least your losses will be under control and IF you can win many times in a row (enough to have more on the table than the max bet) then you pocket that money and you could possibly come out of it a winner, and if not then you have only lost at most a set amount of money (assuming of course that you leave the table after having lost your committed bankroll).

    There is one way to be a guaranteed winner at roulette, craps , baccarat and other games of pure chance: don't play them, and you can count all of the money that you would have bet as winning. In any game where your opponent (the house) has winning odds, they always win in the end. After all, who do you think pays for all of the opulence of these casinos, and the billions of dollars to develop one casino resort? If there was a system to win all casinos would be broke by now (or at least not spinning the roulette wheel).

    Now, this does not necessarily apply to games that are games of both chance AND skill, including blackjack, gin rummy, bridge, poker, etc. BUT, with many games of skill you are often playing against skilled opponents (not the casino), and if your opponents' skills are much higher than yours, you are actually better off (in the long run) playing games of pure chance - i.e. lack of skill = big loser (almost all the time).

    WARNING: NEVER EVER EVER gamble with money that you need for something else (food, rent, etc). Stories of people that win that million in one shot are much much more frequent in movies, TV and the like than in real life. Envisioning it will not cause it to happen, no matter how much you "try." It's all BS - believe me, I know!

    Anyway, as you can see I love to write, but not about this anymore. Best of Luck!!

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  • Anonymous
    1 decade ago

    This is known as a martingale. It is the oldest sure fire way known to go broke. The longest recorded single colour runs on roulette are well over 20 repetitions, and you would need to be staking in excess of $20 to the power of 20 to win back your initial $20 stake, to beat such a run.

    All casinos have 'maximum stake' rules to stop these things from going too far.

    If you want to go broke quicker, you can try a 'Grand Martingale', and triple your stake instead of doubling it.

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  • Player
    Lv 5
    1 decade ago

    Minimum bet $5, maximum $200 this allows you 5 doubles.

    Minimum bet $25, maximum $500 this allows you 4 doubles.

    Minimum bet $5, maximum $500 this allows you 6 doubles.

    Minimum bet $25, maximum $1000 this allows you 5 doubles.

    The maximum bets are set to allow you to double a limited amount of times it's usually 5 or 6.

    Source(s): Me Casino Manager.
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  • Anonymous
    1 decade ago

    nope. regardless of how many times you double, the only way raising your initial stake will increase winnings is if the odds are in your favor, and they will never be in your favor in roulette, where past results do not affect future results, as compared to blackjack.

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  • 4 years ago

    roulette probability question

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  • ?
    Lv 4
    3 years ago


    Source(s): Winning Sport Picks
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