In roulette, a bet on black has a probability of 18/38 of winning. This is because there are 18 black numbers out of a total of 38 numbers on the roulette wheel (including 0 and 00 in American roulette). If you win the bet, you double your money. For example, if you bet $10 and win, you will receive $20 in total ($10 original bet + $10 profit). You can bet anywhere from $1 to $100 on each spin. If you start with $10 and decide to play, you need to consider the risk and potential outcomes of each bet.