Naked pair
The naked pair is a basic sudoku solving technique that you need to master.
Principle
A naked pair is a set of two cells belonging to the same row, column, or region, and having the two same numbers for candidates, and only these two numbers.
In the grid solution, these two numbers will necessarily be in these two cells. Therefore, they can be eliminated as candidates from all the other cells of the row, column or region shared by the pair.
Examples
Example 1 : naked pair on a row
On row B, cells B1 and B8 have the two same candidate numbers : 2 and 3. Therefore, these two numbers can be eliminated as candidates from all the other cells of row B, here B2 and B3.
Example 2 : naked pair on a column
On column 3, cells A3 and K3 have the two same candidate numbers : 3 and 6. Therefore, these two numbers can be eliminated as candidates from all the other cells of column 3, here F3 and H3.
Example 3 : naked pair on a column and a region
Cells A6 and C6 have the two same candidate numbers : 1 and 7. These two cells belong to the same column and region (column 6 / region 2). Therefore, 1 and 7 can be eliminated as candidates from all the other cells of column 6 (F6 and G6) and region 2 (A4, C4, C5).
Exercises
These sudoku grids need to use the naked pair technique in order to be solved :
- Sudoku n°493757 (Easy)
- Sudoku n°2720 (Easy)
- Sudoku n°126453 (Medium)
- Sudoku n°203564 (Medium)
- Sudoku n°308728 (Medium)
You can also challenge yourself with our daily sudokus, the easy and medium levels regularly contain naked pairs.