PlaySudoku.us
Hard · Puzzle #775
9
3
4
1
7
5
4
8
6
2
4
5
7
9
9
4
2
4
3
8
3
1
5
8
4
9
1
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.
"The cosmos is within us. We are made of star-stuff." — Carl Sagan
"The cosmos is within us. We are made of star-stuff." — Carl Sagan