7
5
5
3
8
2
6
1
9
2
1
7
3
5
9
8
2
3
2
4
9
6
2
3
7
4
2
6
2
9
6
4
The 4×4 mini-Sudoku is called 'Shidoku' and can be solved without any pencil marks — it's a common puzzle for children.
The 4×4 mini-Sudoku is called 'Shidoku' and can be solved without any pencil marks — it's a common puzzle for children.
Check columns before rows — columns are often harder to complete and contain more useful constraints.
Check columns before rows — columns are often harder to complete and contain more useful constraints.