PlaySudoku.us
Easy · Puzzle #19
4
9
6
5
2
8
6
1
5
3
5
2
3
8
7
9
4
6
7
1
9
5
2
3
4
7
2
1
3
4
1
9
5
1
8
9
6
7
2
1
4
6
9
4
7
2
3
1
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.