Roulette: Betting strategies and tactics: Betting multiple times

This type of bet is a combination of the red bet and the martingale system. The difference is that this bet also includes the odd. This strategy starts off with a bet of 1 on each the red and the odd (or you can do the black and even). Each bet is treated separately. When one bet loses, it is doubled. When one bet wins, it gets set it back to 1. The reason that this technique keeps the player in the game so long is that there is almost a 25% chance of winning both the red and the odd and there is almost a 50% chance of breaking even (win one bet and lose the other). Of course, in order for this method to last, the player would need an unlimited source of money, and a casino with another one to boot. In reality, this method backfires when the player can't bet any longer and loses. The loss that this causes is possibly hundreds of times bigger than a loss made when starting. Also, in the long run, because the house still has an edge, the player will lose money just like with all other "unbeatable" casino games.

From Wikipedia's

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