Seldom Bucket
Well-Known Member
To Win This Numbers Game, Learn to Avoid Math Patterns
Here’s a simple number game to play on a rainy day, or while sheltering in place. You and I take turns crossing out numbers from the list {1, 2, 3, …, 9}. The winner is the last person to cross out a number without making three crossed-out numbers in a row. Let’s play! You can go first.
Suppose after four moves we’ve crossed out these numbers:
1 2 3 4 5 6 7 8 9
It’s your turn again. Notice if you cross out 4 you lose, as that makes three in a row: 3-4-5. You also lose if you cross out 7, as that makes 7-8-9. Your only safe plays are to cross out 1, 2 or 6. But no matter which number you choose, I can cross out one of the others and win by leaving you with no safe moves.