PlaySudoku.us
Evil · Puzzle #855
8
4
6
5
1
5
9
3
3
7
1
5
6
1
9
3
3
2
6
5
7
1
8
4
9
Techniques used
- Hidden Single
- Naked Triple
- Pointing Pair
- Naked Single
- Hidden Pair
- W-Wing
- 2-String Kite
- XY-Chain
- Naked Pair
- UR Type 1
- Forcing Chains
Set theory provides the formal foundation for Sudoku's rules: each digit must appear exactly once per set.
Set theory provides the formal foundation for Sudoku's rules: each digit must appear exactly once per set.
When a box has only two empty cells, you know exactly which two digits fill them.
When a box has only two empty cells, you know exactly which two digits fill them.