Hidden Pair

Basic

Two digits are confined to the same two cells in a unit; all other candidates in those cells are eliminated.

How It Works

When two digits can only appear in the same two cells within a unit, those two cells must contain those two digits. Therefore all other candidates in those two cells can be eliminated.

Example: If 4 and 7 are only candidates in R2C3 and R2C5 within row 2 → Remove all other candidates from those cells.

Example

25
39
16
47
28
19
35
67
48
17
48
25
36
19
47
28
35
16
39
16
47
25
38
16
49
27
35
28
37
15
49
26
38
17
45
29
16
45
29
37
18
25
36
48
17
2789
3641
1258
975
37
26
18
45
39
27
46
15
28
15
48
37
26
14
39
25
38
16
29
15
46
38
27
14
38
26
39
Key cells of the techniqueCells where elimination is appliedCandidate to be placedEliminated candidate (crossed out)

Row 6: Digit 2 only appears in R6C4 and R6C7; digit 8 also only in R6C4 and R6C7 → R6C4 = {2,8}, R6C7 = {2,8}, all other candidates removed.

Practice with a Real Puzzle

This 9×9 puzzle is solver-verified to require this technique on its solution path.

Easy32 givensStrict