PlaySudoku.us
Easy · Puzzle #348
1
7
8
4
9
2
8
9
5
4
3
7
1
7
9
2
6
5
6
9
3
8
3
4
5
2
9
7
1
3
5
4
8
6
5
7
6
1
8
9
6
2
3
9
1
7
8
7
2
3
Scan by digit rather than by cell: find everywhere '7' must go before switching to '8'.
Scan by digit rather than by cell: find everywhere '7' must go before switching to '8'.
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.