What it is
A naked pair is two cells in the same row, column or box whose candidates are exactly the same two digits. Those two digits must occupy those two cells (in some order), so they can be eliminated from every other cell of the unit.
How to spot it
Keep pencil marks tidy and look for two cells in one unit showing an identical two-digit note. The tighter your notes, the more pairs appear.
Interactive example
Use Next to walk through the deduction on the board.
Step by step
- This row is missing 2, 7 and 8, spread across three empty cells.
- Two of the cells allow only 2 and 7 — the 8s in their column and box already exclude 8 from them. That's a naked pair.
- 2 and 7 must occupy the pair's two cells, so they can be removed from every other cell in the row.
- The third cell has only 8 left — the pair produced a placement.
Common mistake: Applying it when one of the two cells has a third candidate. {2,7} and {2,7,8} is not a naked pair — both cells must contain exactly the same two digits and nothing else.
Put it into practice
Examples on this page are validated with the Play Sudoku Daily puzzle engine.