How to Win Every Bet

Richard Wiseman is Britain's only professor for the Public Understanding of Psychology at the University of Hertfordshire, and a reknowned voice in the fields of luck, self-help and illusion. With a background in magic and psychology, Richard traveled the globe for years in search of the world's greatest bets. He has compiled 101 of the best bets in his new book, 101 Bets You Will Always Win. 

Today, he joins Math Dude Jason Marshall for a short interview to discuss how probability and mathematics can play a role in winning bets.

Q: I want to talk about some of the mathematical ideas that support a good bet. For instance, how can probability help us make better decisions when it comes to betting?

Richard: Well, we are notoriously bad with probability, which is why Vegas does so well. All those big flashy hotels are not built on the money that people have won in Vegas; they’re built on money that people have lost. So, we’re not very good with probability.

All those big flashy hotels are not built on the money that people have won in Vegas; they’re built on money that people have lost. 

There are all sorts of classic probability problems that can show us that—for example, suppose you meet somebody on the street and they tell you that they’ve got two kids, one of whom is a boy. What’s the chance that the other one is also a boy? You’d think it’s roughly 50-50. In fact, that’s not right. When you work through the probability, it’s actually about 1 in 3. So we’re not good with probability, and some of the bets work because of that, while others are mathematical.

One of my favorite ones is if you say to somebody (and here’s the bet) “You’re going to give me any 3-digit number and within a fraction of a second, I’m going to multiply it by 7, by 11 and then by 13.” It sounds impossible, like you’re a human calculator. But all you need to do is just repeat the number that they’ve just given to you. So, if they say the number is 476, then you just write 476,476 because any 3-digit number when it’s multiplied by 7, by 11, then by 13 simply repeats itself. Why? Because 7 multiplied by 11 multiplied by 13 is 1001, and so the math works out. It’s about these kinds of fun ways to use math as well. 

Try This Bet 

Place five or six pennies on a table and balance another penny on its edge. Ask your friend how many  pennies you will need to stack up to reach the height of the upright penny. They might guess five or six, but you will win the bet because the answer is an amazing twelve coins!

This bet is one of many from 101 Bets You Will Always Win. You can order a copy on Amazon, Barnes & Noble, Indiebound, and Books-a-Million.