How Not to Be Wrong: The Power of Mathematical Thinking

by Jordan Ellenberg

It’s massively improbable to get hit by a lightning bolt, or to win the lottery; but these things happen to people all the time, because there are a lot of people in the world, and a lot of them buy lottery tickets, or go golfing in a thunderstorm, or both. Most coincidences lose their snap when viewed from the appropriate distance. On July 9, 2007, the North Carolina Cash 5 lottery numbers came up 4, 21, 23, 34, 39. Two days later, the same five numbers came up again. That seems highly unlikely, and it seems that way because it is. The chance of those two lottery draws matching by pure chance was tiny, less than two in a million. But that’s not the relevant question, if you’re deciding how impressed to be. After all, the Cash 5 game had already been going on for almost a year, offering many opportunities for coincidence; it turns out the chance some three-day period would have seen two identical Cash 5 draws was a much less miraculous one in a thousand. And Cash 5 isn’t the only game in town. There are hundreds of five-number lottery games running all over the country, and have been for years; when you put them all together, it’s not at all surprising that you get a coincidence like two identical draws in three days. That doesn’t make each individual coincidence any less improbable. But here comes the chorus again: improbable things happen a lot. Aristotle, as usual, was here first: despite lacking any formal notion of probability, he was able to understand that “it is pr...

Australian lottery numbers 4,5,6,7,8 are questioned as being faked