PlaySudoku.us
Easy · Puzzle #550
3
5
8
2
1
9
6
1
4
6
1
9
2
2
4
7
6
9
7
1
5
8
4
5
4
8
9
6
1
3
4
1
5
2
3
7
8
2
9
1
5
3
7
3
8
9
6
2
4
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.