The presence of zeros gives the house an edge. House Edge: The presence of zeros means that even if you place bets on red or black, odd or even, or other nearly 50/50 propositions, you do not have a true 50% chance of winning. The presence of zeros tilts the odds slightly in favour of the casino.
In American roulette, there is a second green pocket marked 00. Pocket number order on the roulette wheel adheres to the following clockwise sequence in most casinos: Single-zero wheel. 0-32-15-19-4-21-2-25-17-34-6-27-13-36-11-30-8-23-10-5-24-16-33-1-20-14-31-9-22-18-29-7-28-12-35-3-26.