This presentation discusses martingale strategies for playing roulette, making use of the binomial distribution, the Poisson distribution, and the Normal approximation. Some gamblers use a martingale or doubling strategy as a way of improving their chances of winning. Important formulas for the martingale strategy are derived, such as the distribution, the expected value, the standard deviation of the profit, the risk of a loss or the expected bet of one or multiple martingale rounds. A computer simulation study with R of the doubling strategy is presented. Finally, the results of doubling to gambling with a constant sized bet on simple chances and on single numbers (straight bets) are compared.