Roulette streaks

23 October 2016

By John Grochowski

QUESTION: The sign at a roulette table caught my eye. It said the last two numbers had been 6, the one before that was 5, and before that another 5 and a 4.

So in the last five spins, the only numbers that had come up were 4, 5 and 6.

It was too tempting to pass up. I bought in and made bets totaling $10: $6 on the 4-5-6 street and $2 each on the 1-2-3 and 7-8-9 streets. I figured if the numbers were repeatedly in that neighborhood, that was my best chance.

It didn’t work out. The next number was 28, and the one after that 19. I don’t usually play roulette, so I left after losing $20.

Would you have been tempted? Were those the right bets to make?

ANSWER: No, I would not have been tempted. If I was playing roulette and that sequence of numbers came up, I’d just keep playing my usual numbers – family birthdays, anniversaries and the like.

Every number has an equal chance of winning on every spin. That there were three sixes within five spins does not establish that there’s any kind of bias to the wheel that would lead the number to come up more often than by chance.

Modern casinos are careful enough in maintenance that biased wheels are rare. Establishing that a bias exists and that a streak is not just a random quirk takes observation and analysis of thousands of spins.

As for betting numbers in the neighborhood, 4, 5 and 6 are neighbors on the betting layout, but not on the wheel itself. The numbers on either side of 6 on the wheel are 18 and 21, and their next neighbors are 31 and 33.

The 5 slot is directly opposite the 6, half a wheel away, while the 4 is four slots away from the 6 as you go from 6 to 21, 33, 16 and then 4.

If you want to bet on a number and its neighbors, thinking a wheel bias is leading the ball to land in a certain segment, you want to look at neighbors on the wheel rather than on the layout.

Far more likely than a bias is that you saw a random streak.


QUESTION: It seems like every year I see fewer and fewer blackjack tables and more and more with Three Card Poker, Mississippi Stud, Ultimate Texas Hold’em and other, newer games. Yet the tables that are always full are the blackjack tables. When traffic is light in the casino and they don’t have all the tables open, it’s the new games that are shut down.

Why is that? Why don’t they just give us more blackjack, since that’s the game we want to play?

ANSWER: Blackjack presents casino operators with a problem. It’s been the most popular table game for more than half a century, but it’s also a game that can be beaten. Even the overwhelming majority who can’t beat it can use basic strategy to get the house edge under 1% if blackjacks have the traditional 3-2 payoffs.

The result has been toward devoting more space to other games as well as toughening blackjack rules. The games you mention appeal more to low-limit bettors than to big players. They also have higher house edges than blackjack, enabling operators to squeeze more profit out of low-limit tables.

Casinos that pay only 6-5 on blackjacks – mostly on low-limit tables – hike the house edge by 1.4%. That puts blackjack in the same realm as the poker-based games you mention.