A Naked Pair occurs when two cells in a row, column, or block share exactly the same two candidates, and no other candidates exist in those cells. These two candidates must be placed in those two cells, eliminating them from other candidates in the same row, column, or block.
- Identify two cells within the same row, column, or block with identical pairs.
- Eliminate these two numbers from the other cells in the affected area.
- Repeat throughout the grid to uncover new solutions.
In Row 1, columns 1 and 4 are the only cells containing the candidates 6 and 8. Since these candidates must occupy these two cells, 6 and 8 can be eliminated as possibilities from the other cells in Row 1. This leaves only one valid candidate for the cell in column 2, solving it with the number 5.
It contains all three techniques discussed so far: Naked Single, Hidden Single, and Naked Pair.
How to spot it
Find two cells in the same unit that each show the very same two candidates and nothing else. Those two digits are locked into those two cells.
When to use it
Use it when singles dry up. A Naked Pair does not place a digit; it removes candidates, often opening up new singles.
Common mistakes
- Requiring the two cells to be identical only; they must be in the same row, column, or box to interact.
- Forgetting that the eliminations apply to every other cell in the shared unit, not just neighbouring cells.
Frequently asked questions
- What is a Naked Pair in Sudoku?
- A Naked Pair is two cells in the same row, column, or box that contain only the same two candidates. Because those two digits must occupy those two cells, they can be eliminated from every other cell in that unit.
- How does a Naked Pair help you solve a puzzle?
- It does not place a digit directly. Instead it removes those two candidates from the rest of the shared unit, which frequently exposes a Naked or Hidden Single you can then place.
- What is the difference between a Naked Pair and a Hidden Pair?
- A Naked Pair shows only the two candidates in each cell. A Hidden Pair is two digits confined to two cells that also contain extra candidates; you remove the extras to reveal the pair.