Techniques › Hidden Pair
Hidden Pair
Two digits that can only go in the same two cells own them, whatever else those cells show.
Two digits in a house whose remaining positions are exactly the same two cells. Those two cells must take those two digits between them, so every other candidate in those cells can be cleared.
A Hidden Pair is the counterpart to the Naked Pair, and the harder of the two to see: instead of two cells that look obviously linked, you are looking for two digits that happen to share the same two homes while the cells are still cluttered with other possibilities. Finding one often unlocks a cell that looked hopeless.
A worked example
Taken from a real puzzle in our bank, at the point where this was the cheapest move available. Pattern candidates are marked in amber; anything the step eliminates is struck through in red.
| 2 | 3 | 5 | 14 | 46 | 146 | 7 | 8 | 9 |
| 4 | 7 | 1 | 9 | 3 | 8 | 2 | 5 | 6 |
| 8 | 9 | 6 | 7 | 2 | 5 | 3 | 4 | 1 |
| 6 | 8 | 7 | 24 | 1 | 24 | 9 | 3 | 5 |
| 9 | 1 | 2 | 5 | 7 | 3 | 8 | 6 | 4 |
| 3 | 5 | 4 | 6 | 8 | 9 | 1 | 2 | 7 |
| 7 | 46 | 3 | 8 | 9 | 46 | 5 | 1 | 2 |
| 15 | 24 | 9 | 3 | 45 | 124 | 6 | 7 | 8 |
| 15 | 26 | 8 | 12 | 56 | 7 | 4 | 9 | 3 |
- NudgeSome digits in box 8 can only go in the same few cells, so nothing else fits there.
- WhereHidden Pair in box 8: r8c6, r9c4
- Do itRemove r8c6 ≠ 4
How to spot it
Count homes per digit within a house. Any two digits with exactly two homes each — and the same two — are a Hidden Pair.
Where you will meet it
Hidden Pair sits at tier 1 of our ladder, which means it first becomes necessary at Easy. Puzzles below that band never require it, though it may still appear as a shortcut.
Read next
- Naked Pair Two cells in a house holding the same two candidates lock those digits away from the rest.
- Hidden Triple Three digits restricted to the same three cells clear everything else out of them.
- Claiming A digit confined to one box inside a line clears that digit from the rest of the box.