A Toronto statistician picked winning lottery tickets with 95% accuracy before buying them.
Mohan Srivastava, a geological statistician, realized that the apparent randomness of the Tic Tac Toe scratch ticket was a mathematical lie and this meant that the lottery system might be solvable.
After only a few hours of studying the tickets, and some statistical sleuthing, he discovered the defect in the game: The visible numbers revealed essential information about the digits hidden under the latex coating. Nothing needed to be scratched off to determine the winning tickets.
Instead of secretly plundering the game, he decided to report the problem to the Ontario Lottery and Gaming Corporation. He sent them a batch of unscratched tickets, sorted into winners and losers. Srivastava correctly predicted 19 out of the 20 tickets.
The next day, the Tic Tac Toe game was pulled from stores. But similar scratch lotteries are still being played all over the world.