Crosshatching
Follow the rows and columns that cut through the box and already hold the digit; one cell is left. No written candidates needed.
How it works on this board
9 has only one place left
8
9
6
3
7
6
5
4
1
2
9
4
5
4
6
1
6
4
8
3
7
2
7
6
4
1
9
2
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