Naked Pair
Naked Pair is a Number Place technique. When two cells in the same row, column, or block have exactly the same two candidate numbers, those two numbers must go in those two cells. Therefore, you can eliminate those numbers from other cells in the same area.
How to Use Naked Pair
Note the candidate numbers for each cell.
Look for cells with exactly two candidates in the same row, column, or block.
If two cells have exactly the same two candidates, that’s a Naked Pair.
Remove the pair’s two numbers from the candidates of other cells in the same area.
Example
Suppose a row has 5 empty cells, and two of them have only ‘4, 9’ as candidates. Since ‘4’ and ‘9’ must go in these two cells, you can remove ‘4’ and ‘9’ from the candidates of the other 3 empty cells. For example, a cell whose candidates were ‘4, 7, 9’ would have ‘4’ and ‘9’ eliminated, leaving only ‘7’.
Tips for Finding Naked Pairs
Finding Naked Pairs requires noting candidate numbers for each cell. Cells with only two candidates stand out, so focus on those first. When a Naked Pair is found, candidates can be reduced significantly, often revealing additional singles or pairs in a chain reaction.