PlaySudoku.us
Easy · Puzzle #172
2
7
3
6
1
4
8
3
2
5
4
2
1
7
9
5
9
3
1
2
4
6
9
4
9
1
3
8
2
2
7
4
1
9
7
3
1
6
2
4
1
4
9
8
7
The hardest Sudoku puzzles require techniques equivalent to propositional logic — the same foundation used in computer proofs.
The hardest Sudoku puzzles require techniques equivalent to propositional logic — the same foundation used in computer proofs.
The hardest Sudoku puzzles require techniques equivalent to propositional logic — the same foundation used in computer proofs.
The hardest Sudoku puzzles require techniques equivalent to propositional logic — the same foundation used in computer proofs.