Start with the idea
Start with two numbers in one row, column, or 3x3 box. In this example, column 7 still needs 1 and 9, and only two cells in that column can hold them. Those cells are reserved for 1 and 9, so their extra notes can be erased.
Look for this pattern
Look for a small group of squares in the same row, column, or box. The group can reserve a matching set of numbers.
This empty board keeps the puzzle numbers out of the way so the pattern is easier to see.
Example
5
3
7
6
5
1
4
9
9
8
6
8
6
2
4
5
3
4
8
3
1
7
2
6
6
1
5
9
8
4
1
9
8
2
5
7
Look here firstLook down this column and focus on 1 and 9. Those two numbers can only go in the same two cells.
This technique cleans up candidates inside the pair cells.
Keep 1 and 9 in the two highlighted cells, and erase the other notes from those two cells.
- Scan one row, column, or 3x3 box by number.
- Find two numbers that appear in the same two cells.
- Keep those two numbers there and remove the extra notes.
1 and 9 to keepextra notes to erase
When to look for it
Use it when a row, column, or box has two digits that share the same two possible cells.
How to use it
- Scan a row, column, or box by digit.
- Find two digits that appear in exactly the same two cells.
- Keep only those two digits in the pair cells.
Common mistakes
- Hidden pairs often look noisy because the cells still contain extra notes.
- Do not remove the pair digits from the pair cells; remove the extras.