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by doodpants 1 hour ago
Because there's already another 6 on the same main diagonal. This is an "X Sudoku" puzzle, which means that each main diagonal must have all 9 different numbers.
1 comments
neogodless 1 hour ago
All I've never done the diagonals before... oops.

https://imgur.com/a/Dfxf9CJ (before picking 2 / 6 / 7.)

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