Sep

25

2012

# A Roulette Player Asks Odds of a Win Streak On Birthday and Anniversary Numbers

Picking roulette numbers rarely shifts into the realm of science. Much less than once in a blue moon, a player might discover a biased wheel, where some numbers come up more than you’d expect by random chance. But for all practical matters, roulette is a game of pure chance.

Chance turned in an old friend’s favor at the roulette table, in an unscientific sort of way.

“I wanted my wife’s birthday, Oct. 26, so I bet \$2 on 10 and \$2 on 26,” my friend Greg explained. “Then I took a third \$2 and put it on our anniversary, the 18th. The first spin was 26, so I won right away. The second spin was 18, so now I’d won on both a birthday number and the anniversary. And this is what floored me. The third spin was 10. I’d won single-number bets on the first three spins we were playing, with three different numbers.”

“What are the odds of that?”

With three single-number bets on a double-zero wheel, he had a 3 in 38 chance of winning on each spin — 1 in 12.67. His chances of winning on three consecutive spins were 1 in (12.6667 times 12.6667 times 12.6667), or about 1 in 2,032.

The odds are much higher against winning in that particular sequence — 26, followed by 18, followed by 10. Then the chance of winning is 1 in 38 on each spin, and the chance of all three coming through is 1 in (38 x 38 x 38), or 1 in 54,872.

Greg may never have a streak quite like it again, but you can bet he’ll keep playing those numbers.