Naked Pair

Level: first needed in Expert puzzles. In one line: Two cells in a unit share the same two candidates, so those numbers are removed from the rest of the unit.

A Naked Pair is two cells in the same row, column or box that both have exactly the same two candidates, for example {5, 6} and {5, 6}. One of them will be 5 and the other 6; we don't know which yet, but together they use up both numbers.

That means no other cell in that unit can be 5 or 6. Remove both numbers from all the other cells of the row, column or box the pair shares (if the pair is in the same row and the same box, you can clear both).

Example from a real puzzle

This position comes from an Extreme puzzle in Sudoku Arena, at the exact moment the Naked Pair is the next logical move. Cells are named by row and column: R3C4 means row 3, column 4.

R1C7, R4C7 hold only {5,6} in column 7. Result: remove 6 from R2C7, 5 from R3C7.

Play this puzzle and look for the move yourself. It's a practice game, so it doesn't count towards your stats.

How to spot it

1. Write candidates as notes in the cells of the area you are studying.
2. Look for two cells in one unit with exactly two notes each, and the same two.
3. Remove those two numbers from every other cell in that unit.
4. See if the removals created a single anywhere.

Tips

• Both cells must contain exactly those two candidates and nothing else; a cell with {5, 6, 8} does not count.
• Pairs are easy to see once notes are in, which is one reason good players write notes on harder puzzles.

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