8
4
1
3
6
3
4
9
2
7
2
4
2
6
3
6
1
7
2
2
4
3
6
7
5
4
5
8
2
2
7
"Chess demands total concentration." — Bobby Fischer
"Chess demands total concentration." — Bobby Fischer
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.