How Naked Pairs Work in Sudoku

Confirm the pair precisely

The two cells must share a unit and each must contain only the same two candidates, such as {3, 8} and {3, 8}. A cell containing {3, 8, 9} does not belong to the naked pair because the third candidate means the two digits are not locked there. Likewise, matching notes in cells that do not share a row, column, or box produce no elimination.

Once the pair is valid, one cell will be 3 and the other will be 8, even though you may not yet know the order. No third cell in that unit can use either digit.

Eliminate within each shared unit

If the pair cells share only a row, remove the two candidates from other cells in that row. If they also sit in the same box, the pair is valid in both units and can support eliminations in both. Treat each unit independently and verify that both pair cells belong to it before removing anything.

Find pairs without scanning randomly

After updating full candidates, inspect units containing several two-candidate cells. Group those cells by candidate set. Repeated sets are worth checking, while visually similar sets such as {2, 7} and {2, 9} are not pairs. After every elimination, search for a newly exposed single before hunting for another advanced pattern.

1. Choose one row, column, or box.
2. Find cells with exactly two candidates.
3. Match two cells whose candidate sets are identical.
4. Remove both digits from other cells in the shared unit.
5. Check whether the eliminations create singles or another locked set.

Avoid the most common false pair

Two digits appearing only twice in a unit are not automatically a naked pair if either cell contains extra candidates. That situation may describe a hidden pair, which uses different evidence and requires different cleanup. For a naked pair, the restriction is visible in the two cells themselves: exactly two cells, exactly two candidates, same unit.