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How many squares of any size on this chessboard do not contain a rook?
Puzzle Copyright © Kevin Stone
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Answer
There are 125 squares without a rook.
Reasoning
61 squares of size 1 x 1
39 squares of size 2 x 2
20 squares of size 3 x 3
5 squares of size 4 x 4
Giving a total of 61 + 39 + 20 + 5 = 125 squares.