PlaySudoku.us
Evil · Puzzle #188
7
3
8
4
8
6
1
6
8
2
7
5
4
8
3
4
5
2
1
6
7
7
9
5
Techniques used
- Naked Single
- Hidden Single
- Pointing Pair
- X-Wing
- XY-Wing
- 2-String Kite
- W-Wing
- Skyscraper
- Box-Line Reduction
The pigeonhole principle explains why 8 clues are never enough to guarantee a unique Sudoku solution.
The pigeonhole principle explains why 8 clues are never enough to guarantee a unique Sudoku solution.
Retired architect Howard Garns, who invented the modern Sudoku, never knew it became a global phenomenon — he died in 1989.
Retired architect Howard Garns, who invented the modern Sudoku, never knew it became a global phenomenon — he died in 1989.