How it works
Naked pairs are the first elimination technique most solvers learn. They do not place a digit directly. Instead they remove candidates from other cells, which often produces a naked or hidden single elsewhere.
The pattern is precise. Two cells in the same unit must have exactly the same two candidates, with no extras. For example r1c3 contains {2, 7} and r1c7 also contains exactly {2, 7}. Now 2 and 7 are locked into those two cells, so any other cell in row 1 with 2 or 7 as a candidate can have them eliminated.
Naked pairs often hide because pencil marks accumulate over the course of a solve. If a cell shows three candidates but two are already eliminated by recent placements, that cell may actually be a pair candidate. Stay disciplined with your marks.
When to look for it
Once pencil marks are laid down. Scan each row, column and box for two cells with identical 2-candidate sets.
Tips for spotting the pattern
- Scan units with the fewest empty cells first. Naked pairs there are most visible.
- After eliminating from peers, immediately re-scan for singles. Pairs often cascade.
- If you find a naked pair but no eliminations follow, the pair was already implicit.
Common mistakes
- Calling a near-pair a real pair. Both cells need exactly the same two candidates, no more.
- Forgetting to apply the eliminations. The pair itself does not place anything; the eliminations do.
- Confusing naked pairs with hidden pairs. Naked is about the cells, hidden is about the digits.