When two cells in the same row, column, or box can only contain the same two numbers, those numbers cannot appear anywhere else in that group. Simple idea, big results.
What is a naked pair?
A naked pair happens when two cells in a row, column, or 3x3 box share exactly the same two candidates. Since those two numbers must go in those two cells, you can remove them from all other cells in that group.
Two cells both have only 2 and 7. Remove 2 and 7 from other cells in this row.
How it works
Think about it: if two cells can only hold 2 and 7, one gets the 2, the other gets the 7. We do not know which is which yet, but we know no other cell in that row, column, or box can have either number.
- Find two cells in the same group with identical candidates (exactly two numbers).
- Check that both cells have only those two candidates, nothing else.
- Remove those two numbers from all other cells in that group.
Why does this help?
Eliminating candidates often reveals naked singles or other patterns. One naked pair can unlock several cells.
Cells with 3,8 form a pair. Remove 3 and 8 from other cells in this box.
Spotting them faster
- Look for cells with only two candidates first.
- Boxes are easier to scan than long rows or columns.
- After finding a pair, check if eliminations create new singles.
Practice
Naked pairs show up often in medium and hard puzzles. Once you train your eye, you will spot them quickly.