Naked pair
Two cells in the same unit whose candidate sets are identical and contain exactly two digits. Together they claim those digits across that unit and rule them out elsewhere.
A naked pair is two cells in the same unit whose candidate sets are identical and contain exactly two digits. Because those two digits have to live in those two cells — there's nowhere else within the unit they could go — they can be eliminated from every other cell in that unit.
How to spot one
Two cells in a unit, both showing exactly the same pair of pencil-marked candidates. Common shapes: two cells both pencil-marked {3, 7} in the same row; two cells both pencil-marked {2, 8} in the same box. The cells don't have to be adjacent — they just have to share a unit.
The argument is symmetric. Cell A has candidates {3, 7}; cell B has candidates {3, 7}; the unit contains both cells; so the 3 must go in one of them and the 7 in the other. We don't yet know which way round, and it doesn't matter — every other cell in the unit can have 3 and 7 ruled out, full stop.
When you'll see it
Naked pairs are common from medium puzzles upward. They often unlock the next move rather than producing a placement directly: eliminating 3 and 7 from a third cell can collapse that cell to a single remaining candidate, which becomes a naked single, which cascades. The naked pair itself is rarely the placement — it's the elimination that enables one.
Why "naked"
"Naked" because the pair's claim is exposed: both cells show exactly those two digits, nothing more. The hidden version of this move — the hidden pair — is the same logical claim approached from the digit-first perspective, where two digits have only two possible cells in the unit even if those cells still appear to carry other candidates.
For a longer take on naked vs hidden pairs and the symmetric logic, see Naked and hidden pairs and triples.
See also
- Hidden pair— Two digits whose only possible cells inside a unit are the same two cells — even if those cells still show other candidates. The digit-first sibling of the naked pair.
- Naked triple— Three cells in the same unit whose candidates collectively use only three digits. Together they claim those digits across the unit and rule them out elsewhere.
- Naked single— A cell on the Sudoku grid that has only one legal candidate left — the simplest deduction in the game, and the one that solves most of an easy puzzle.
- Candidate— A digit (1–9) a cell could still legally hold — one not yet ruled out by anything in its row, column, or 3×3 box. Every empty cell has between one and nine.
Read more
- Naked and hidden pairs and triples
The mid-level extension of singles — how pairs and triples work, when each shows up, and the perspective shift that surfaces them.