There are 36 numbers on a standard roulette wheel. The numbers run from 1 to 36, with one spot left open at number 37.
Numbers 1 through 18 are called the “common numbers,” while 19 through 36 are known as “natural numbers.” Roulette wheels with more than one track also have other numbers, such as 00 (zero), 06, or 10.
When you place a bet on a roulette wheel, you’re betting on one of the 36 possible outcomes. The odds of any particular number appearing on the wheel are 1 in 36.
So if you bet $10 that the number 7 will show up on the wheel, your odds of winning are $36 – or 10% of your total bet. If the wheel does show 7, you win your $10 back plus whatever additional money was bet on that number – in this case, $11.
