A roulette wheel typically has two "House" betting spots, one labeled zero, the other double zero. The House wins all even, odd, red, black and number bets when the ball lands in the zeros. This is the House advantage. At one time, and perhaps some European casino still offer, casino roulette had only on zero. With two zeros, the House has an advantage of a little over 5.25%, half that for single zero. Does that answer your question? This is all the information you need to know about roulette. Don't play roulette.