1
2
3
4
5
6
7
8
9
456789
456789
456789
123789
123789
123789
1234569
1234569
1234569
456789
456789
456789
123789
123789
123789
1234569
1234569
1234569
23456789
13456789
12456789
12356789
12346789
12345789
12345689
12345679
123456789
23456789
13456789
12456789
12356789
12346789
12345789
12345689
12345679
123456789
23456789
13456789
12456789
12356789
12346789
12345789
12345689
12345679
123456789
23456789
13456789
12456789
12356789
12346789
12345789
12345689
12345679
123456789
23456789
13456789
12456789
12356789
12346789
12345789
12345689
12345679
123456789
23456789
13456789
12456789
12356789
12346789
12345789
12345689
12345679
123456789
Naked Single
A naked single is a cell whose row, column and box between them already use eight of the nine digits — so only one candidate remains for that cell. Place it.
There's a move in the top-right box.