579
Techniques · Medium
Naked Pair
Two cells in the same unit that both hold exactly the same two candidates will take those two digits between them, one each. No other cell of the unit can have either digit.
How to spot it
Look for two cells with the same two notes, such as 3/7 and 3/7, in one row, column or box. Clear 3 and 7 from every other cell of that unit.
Example
8
569
1
3
4
567
2
57
2
3
1
78
6
5
47
489
479
57
4
56
78
9
2
1567
18
3
59
2
8
3
57
6
47
49
1
3
1
59
4
57
8
2
6
79
6
7
4
9
2
1
3
5
8
1
9
2
5
4
7
8
3
6
48
5
7
6
18
3
9
14
2
48
6
3
2
18
9
145
7
45
In column 7, r2c7 and r4c7 can only hold 4 and 7, so 4 and 7 can be removed from the other cells of column 7 (Naked Pair).
the pattern cells that lose a candidate (crossed out)