If you bet $100, your odds of winning are around 50% and if you lose, bet $200, and so on and so forth until you win, and then cash out with a guaranteed profit. Assuming odds of black are 47.37% as per American roulette, your odds of not winning a single one after 6 tries are 0.02125 (I think) and decrease exponentially after each subsequent try.
In: 93
Theoretically they can. What you’re describing is called the martingale strategy. There are two problems with using it to earn significant money in practice: first, you need to have a lot of money available to you, and second, whenever a casino notices that someone is using a strategy that beats the house reliably the casino just bans them (the casino doesn’t need a reason to stop someone from gambling).
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