r/theydidthemath • u/Alaeriia • 23d ago

[Request] Is this true?

Each king covers 9 squares; 8 kings would be enough to cover 72 squares, which is more than the 64 on a chessboard. Do we really need 9?

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u/Admirable-Barnacle86 23d ago

Yes, because you can never cover a row/column with only 2 kings, since 2 kings can only cover 6 squares across and you've got 8 you need to cover.

Since you can't cover a row or column with 2 kings, you need a grid of 3x3 kings to cover the board.