PlaySudoku.us
Easy · Puzzle #646
4
2
9
3
2
8
3
4
9
3
7
8
1
2
5
6
4
1
8
7
5
2
3
1
4
9
8
7
9
6
2
9
6
2
5
3
8
3
8
5
4
6
1
6
5
3
1
9
"Mathematicians do not study objects, but relations between objects." — Henri Poincaré
"Mathematicians do not study objects, but relations between objects." — Henri Poincaré
The pigeonhole principle explains why 8 clues are never enough to guarantee a unique Sudoku solution.
The pigeonhole principle explains why 8 clues are never enough to guarantee a unique Sudoku solution.