Anonymous ID: edf8a0 March 10, 2019, 8:13 p.m. No.5616473   🗄️.is 🔗kun

Creator Challenge Difficulty Rating: Hard

This month's NSA Puzzle Periodical pays tribute to the 1983 motion picture "WarGames." In the movie a supercomputer is programmed to play Tic-Tac-Toe.

The computer plays itself with each X and O placed uniformly at random into any square (this means the computer plays without regard to strategy). What is the probability a game will end in a draw?

Assume perfect random number generation. The first X will be placed in any square with probability 1/9. The first O will go into any of the remaining squares with probability 1/8 and so on.