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Hard · Puzzle #645
7
5
9
3
1
6
7
4
3
3
5
8
7
2
2
7
6
4
6
7
3
9
1
4
2
8
5
7
Hidden Triple: three digits each appearing in only three cells within a group — eliminate all other candidates from those three cells.
Hidden Triple: three digits each appearing in only three cells within a group — eliminate all other candidates from those three cells.
Group theory classifies Sudoku symmetries: the automorphism group of the 9×9 Sudoku grid has order 1,218,998,108,160.
Group theory classifies Sudoku symmetries: the automorphism group of the 9×9 Sudoku grid has order 1,218,998,108,160.