No matter which version of roulette you pick or what strategy you use, the casino always has an advantage. The house edge is the average percentage of the wager that will be lost by the player in the long run. In American roulette the house edge is 5.3% and the player’s chance of hitting a number is 1/38, while in European roulette it’s 2.7% and the chance is 1/37.
The Martingale betting strategy is one of the most popular ones. Every time you lose, you double your bet. It sounds good, because when you eventually win you will get all the lost money and the original bet back, but in reality you can lose a lot of money in the process.
Betting on the same number for 35 spins of the wheel is a strategy too. If within those spins you hit your number, you get back all the money. It’s a strategy for stretching your bankroll and playing longer rather than making money. In American roulette, the probability of hitting the number within 35 spins is still only 60.68%.
Another strategy is betting on the same color for 38 spins. In American roulette that’s 18 out of 38, which means 47.37% chance of getting the same color 18 times in 38 spins. It would have to be 19 times to break even, so the chance of doing that is 37%.
In land-based casinos it was also a possibility to try to predict where the ball is going to land according to how the spin was going, by using special computer devices to calculate that. Since it doesn’t interfere with the game, it couldn’t be illegal.