Solving techniques
Naked pair
A naked pair does not place a digit. It removes two candidates from the rest of a unit, which often opens a new single.
A naked pair is two cells in the same row, column or box that each contain exactly the same two candidates. Those two digits must go in those two cells, so they can be removed as candidates from every other cell of the unit.
The logic
Suppose two cells in a box both have only 1 and 2 as candidates. One of them is 1 and the other is 2, in some order. Either way, 1 and 2 are used up inside this box, so no other cell in the box can hold them.
How to find a naked pair
- Fill in notes for the unit.
- Look for two cells with exactly two candidates, and the same two.
- Remove those two digits from the other cells of the same unit.
- If the pair is in a row and a box at once, you can clean both units.
Common mistakes
- Treating two cells with different candidates (such as 1 2 and 2 3) as a pair. The two cells must hold the identical pair.
- Removing the digits from the pair cells themselves.
- Working across units: the pair only affects the unit that contains both cells.
What next?
After removing candidates, go back and look for new naked and hidden singles. The same idea with three cells is the naked triple, and the reverse view is the hidden pair.
Frequently asked questions
What is a naked pair?
Two cells in one unit that contain exactly the same two candidates.
What do you do with a naked pair?
Remove those two digits from every other cell in the unit.
Do the cells need to be next to each other?
No. They only need to share a row, column or box.