Mistakes? What Were the Odds of That?

What’s luck got to do with it? The maths of gambling

He wasn’t on a lucky streak, he was using his knowledge of mathematics to understand, and beat, the odds.

“Beat the odds” isn’t quite as bad as “defies the laws of physics,” I think. But exploiting knowledge of the odds to win isn’t beating the odds. Beating the odds is winning when you shouldn’t — drawing to an inside straight and hitting it to win a hand is beating the odds. Exploiting the situation to make the odds go in your favor — making it so you should win more than you lose — is not.

A spin of the roulette wheel is just like the toss of a coin. Each spin is independent, with a 50:50 chance of the ball landing on black or red.

Well, no. A roulette wheel has 37 or 38 slots, depending on where you play, with 36 of them being black or red. The others are green — 0 and 00 (Europe has one, the US has both. Sort of.) That’s why the house makes profit offering “even money” on black or red bets on a US wheel; the probability of winning is slightly less than 50%. (They also make money on the single-number payouts, at 35:1) All of the bets on a 00 roulette wheel have a house advantage of at least 5.26%; single-0 wheels have a smaller house advantage but there also seems to be a correlation with higher-stakes limits. The previous link also presents a section on debunking the “doubling down” method for roulette. Winning at roulette is truly “beating the odds” since the house always has an advantage.

So please don’t follow the advice here. But note this:

For what it is worth, the sum of all the numbers in roulette is 666.

4 thoughts on “Mistakes? What Were the Odds of That?

  1. In the same answer they also promote a betting system called the “Martingale” where you double your stake when you lose. Disastrous…

  2. The House bets on statistics, the players bet on statistical fluctuations. One can trivially show that the drunkards’ walk drifts. The trick is in knowing which direction – beforehand. The House plays a pat hand.

  3. The doubling system works quite well, I’m told. My calculus teacher started with $5 bets and would routinely walk away with several hundred dollars. Although he was kicked out of a casino once…

  4. Reading the link: interesting. So basically the Martingale works until the one time where you don’t have quite enough money to cover your bets. The question is whether someone who plays roulette once or twice a year is likely to ever face that outcome. I know my math teacher reports never having that problem.

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