Naked Pair

Level 3 · Yellow Belt

Strategy:

Requires:

Learn after:

Almost Locked Sets BUG+1 Naked Triple Unique Rectangle Type 1 W-Wing XY-Wing

Overview

A Naked Pair consists of two cells in the same house that contain exactly the same two candidates and nothing else. Since those two digits must occupy those two cells, they can be eliminated from all other cells in the house.

How It Works

Find two cells in the same house that contain exactly the same two candidates.
These two cells will contain those two digits (though we don't know which goes where).
Eliminate both candidates from all other cells in that house.

Example

Look for Naked Pair.

Sudoku grid showing the initial puzzle state for Look for Naked Pair.

1

Naked Pair

Find two cells in column 8 that both have only candidates 1 and 6.

Sudoku grid illustrating step 1: Naked Pair — Find two cells in column 8 that both have only candidates 1 and 6.

2

Naked Pair

Digit 2 cannot go in r2c8 because r2c3 is in this row and r3c7 is in this box. Remove the entry or choose a different digit.

Sudoku grid illustrating step 2: Naked Pair — Digit 2 cannot go in r2c8 because r2c3 is in this row and r3c7 is in this box. Remove the entry or choose a different digit.

3

Naked Pair

Digit 3 cannot go in r2c8 because r2c5 is in this row, r6c8 is in this column, and r3c9 is in this box. Remove the entry or choose a different digit.

Sudoku grid illustrating step 3: Naked Pair — Digit 3 cannot go in r2c8 because r2c5 is in this row, r6c8 is in this column, and r3c9 is in this box. Remove the entry or choose a different digit.

4

Naked Pair

Digit 4 cannot go in r2c8 because r5c8 is in this column and r1c7 is in this box. Remove the entry or choose a different digit.

Sudoku grid illustrating step 4: Naked Pair — Digit 4 cannot go in r2c8 because r5c8 is in this column and r1c7 is in this box. Remove the entry or choose a different digit.

5

Naked Pair

Digit 5 cannot go in r2c8 because r2c9 is in this row and r9c8 is in this column. Remove the entry or choose a different digit.

Sudoku grid illustrating step 5: Naked Pair — Digit 5 cannot go in r2c8 because r2c9 is in this row and r9c8 is in this column. Remove the entry or choose a different digit.

6

Naked Pair

Digit 7 cannot go in r2c8 because r2c7 is in this row and r8c8 is in this column. Remove the entry or choose a different digit.

Sudoku grid illustrating step 6: Naked Pair — Digit 7 cannot go in r2c8 because r2c7 is in this row and r8c8 is in this column. Remove the entry or choose a different digit.

7

Naked Pair

Digit 8 cannot go in r2c8 because r2c2 is in this row and r1c9 is in this box. Remove the entry or choose a different digit.

Sudoku grid illustrating step 7: Naked Pair — Digit 8 cannot go in r2c8 because r2c2 is in this row and r1c9 is in this box. Remove the entry or choose a different digit.

8

Naked Pair

Digit 9 cannot go in r2c8 because r2c1 is in this row and r1c8 is in this column. Remove the entry or choose a different digit.

Sudoku grid illustrating step 8: Naked Pair — Digit 9 cannot go in r2c8 because r2c1 is in this row and r1c8 is in this column. Remove the entry or choose a different digit.

9

Naked Pair

Digit 2 cannot go in r3c8 because r3c7 is already in this row. Remove the entry or choose a different digit.

Sudoku grid illustrating step 9: Naked Pair — Digit 2 cannot go in r3c8 because r3c7 is already in this row. Remove the entry or choose a different digit.

10

Naked Pair

Digit 3 cannot go in r3c8 because r3c9 is in this row and r6c8 is in this column. Remove the entry or choose a different digit.

Sudoku grid illustrating step 10: Naked Pair — Digit 3 cannot go in r3c8 because r3c9 is in this row and r6c8 is in this column. Remove the entry or choose a different digit.

11

Naked Pair

Digit 4 cannot go in r3c8 because r3c3 is in this row, r5c8 is in this column, and r1c7 is in this box. Remove the entry or choose a different digit.

Sudoku grid illustrating step 11: Naked Pair — Digit 4 cannot go in r3c8 because r3c3 is in this row, r5c8 is in this column, and r1c7 is in this box. Remove the entry or choose a different digit.

12

Naked Pair

Digit 5 cannot go in r3c8 because r3c2 is in this row, r9c8 is in this column, and r2c9 is in this box. Remove the entry or choose a different digit.

Sudoku grid illustrating step 12: Naked Pair — Digit 5 cannot go in r3c8 because r3c2 is in this row, r9c8 is in this column, and r2c9 is in this box. Remove the entry or choose a different digit.

13

Naked Pair

Digit 7 cannot go in r3c8 because r3c4 is in this row, r8c8 is in this column, and r2c7 is in this box. Remove the entry or choose a different digit.

Sudoku grid illustrating step 13: Naked Pair — Digit 7 cannot go in r3c8 because r3c4 is in this row, r8c8 is in this column, and r2c7 is in this box. Remove the entry or choose a different digit.

14

Naked Pair

Digit 8 cannot go in r3c8 because r3c5 is in this row and r1c9 is in this box. Remove the entry or choose a different digit.

Sudoku grid illustrating step 14: Naked Pair — Digit 8 cannot go in r3c8 because r3c5 is in this row and r1c9 is in this box. Remove the entry or choose a different digit.

15

Naked Pair

Digit 9 cannot go in r3c8 because r3c6 is in this row and r1c8 is in this column. Remove the entry or choose a different digit.

Sudoku grid illustrating step 15: Naked Pair — Digit 9 cannot go in r3c8 because r3c6 is in this row and r1c8 is in this column. Remove the entry or choose a different digit.

16

Naked Pair

These cells at rows 2 and 3 form a Naked Pair. The two digits must be split between them.

Sudoku grid illustrating step 16: Naked Pair — These cells at rows 2 and 3 form a Naked Pair. The two digits must be split between them.

17

Naked Pair

Because those two cells already have to take 1 and 6, no other cell in the column is allowed to keep those digits.

Sudoku grid illustrating step 17: Naked Pair — Because those two cells already have to take 1 and 6, no other cell in the column is allowed to keep those digits.

18

Naked Pair

These are the other cells in column 8 that still contain 1 and 6 and must be cleaned up.

Sudoku grid illustrating step 18: Naked Pair — These are the other cells in column 8 that still contain 1 and 6 and must be cleaned up.

19

Naked Pair

Remove 1 and 6 from the other cells in column 8.

Sudoku grid illustrating step 19: Naked Pair — Remove 1 and 6 from the other cells in column 8.

20

Result after applying the technique.

Sudoku grid showing the result after applying the technique

Tips & Patterns

Naked Pairs are easier to spot than Hidden Pairs because the cells have exactly two candidates.
Look for cells with only 2 candidates and check if another cell matches.
Naked Pairs often lead to chain reactions of eliminations.