The Naked Pair Technique in Sudoku
The Naked Pair is one of the first techniques beyond simple scanning, and it appears on almost every Hard grid. When two cells in the same row, column or box hold exactly the same two candidates, those two digits belong to that pair — so they can be removed from every other cell in the unit.
How to use a Naked Pair, step by step
- Pencil in candidates so every empty cell shows its possibilities.
- Scan each row, column and box for two cells that show exactly the same two candidates.
- Those two digits are locked to that pair of cells.
- Remove both digits from every other cell in that unit.
- Look for the new singles the eliminations expose.
What is a Naked Pair?
A Naked Pair is two cells in one unit that each contain only the same two candidates — for example both showing {4, 7}. Between them those two cells will use up the 4 and the 7, so neither digit can appear anywhere else in that row, column or box. You do not place a digit; you clear candidates, which then reveals singles.
Naked Pair vs Hidden Pair
A Naked Pair is obvious — two cells showing just two candidates. A Hidden Pair is the mirror image: two digits that can only go in the same two cells, even though those cells still show other candidates. The same idea scales up to the Naked Triple with three cells and three digits.
Naked Pairs in Sudoku: FAQ
What is a Naked Pair in Sudoku?
A Naked Pair is two cells in the same row, column or box that contain exactly the same two candidates. Those two digits are confined to that pair, so they can be eliminated from every other cell in the unit.
What is the difference between a Naked Pair and a Hidden Pair?
A Naked Pair shows only its two candidates in both cells. A Hidden Pair is two digits that can only go in the same two cells, but those cells may still display extra candidates that you then erase.
How do you use a Naked Pair?
Once you find two cells in a unit with the same two candidates, remove both of those digits from all the other cells in that row, column or box. This usually exposes new naked or hidden singles.