cracking lottery codes

http://www.wired.com/magazine/2011/01/ff_lottery/all/1

a tic-tac-toe game. On the right were eight tic-tac-toe boards, dense with different numbers. On the left was a box headlined “Your Numbers,” covered with a scratchable latex coating. If three of “Your Numbers” appeared on a board in a straight line, you’d won.

Mohan Srivastava, trained in geological statistics, reasoned that the numbers are not random, as the makers need to control the number of winners. The patterns would follow rules of geological stats. “But that night, as I passed the station, I heard a little voice coming from the back of my head. I’ll never forget what it said: ‘If you do it that way, if you use that algorithm, there will be a flaw. The game will be flawed. You will be able to crack the ticket. You will be able to plunder the lottery.’”

The trick itself is ridiculously simple. Each ticket contained eight tic-tac-toe boards, and each space on those boards contained an exposed number from 1 to 39. As a result, some of these numbers were repeated multiple times. A few numbers appeared only once on the entire card. Srivastava categorized each number according to its frequency. Srivastava was looking for singletons, numbers that appear only a single time on the visible tic-tac-toe boards. singletons were almost always repeated under the latex coating. If three singletons appeared in a row on one of the eight boards, that ticket was probably a winner.