Sudoku · EN
Sudoku Naked Pairs: Worked Example
A naked pair is two cells in the same unit whose complete candidate lists are the same two digits. They reserve those digits in some order, so remove both from the other cells in that shared row, column or box.
Solver-verified example
Starting grid; dots are empty cells.
Candidates before the move
- R5C4 = {4, 5}
- R5C5 = {4, 5}
Work through this deduction
- In row 5, the complete candidate lists at columns 4 and 5 are both exactly {4,5}. Neither cell has a third option.
- The two cells cannot use the same digit. Together they must take 4 and 5 in some order, reserving both digits in row 5.
- Remove 4 and 5 from the other cells in that row: columns 2 and 7.
- Column 2 is then left with only 7, so write 7 there. The pair itself still has an undecided order.
Eliminate: R5C2 ≠ 4; R5C2 ≠ 5; R5C7 ≠ 4; R5C7 ≠ 5.
Independent verification found one completion. Forcing each displayed eliminated candidate separately produced zero completions. The grid and candidate pattern explain the move; the final answer is a check.
Verified completion
Why this deduction works
Two cells cannot hold the same digit in a unit. Since neither cell has a third option, together they reserve both digits. Matching notes are insufficient if either cell also permits a third digit. Eliminate only in a unit shared by both cells.
Sources and background
Frequently asked questions
Does this move finish the puzzle?
No. It establishes only the stated placement or eliminations. Update affected candidates and continue with another supported deduction.
Are incomplete notes sufficient?
No. Candidates must include every digit still permitted by the row, column and box. Missing a legal candidate can create a false pattern.
