Naked pairs: reserve two candidates
A naked pair appears when two cells in one row, column, or box contain exactly the same two candidates. Those two digits must occupy those two cells in some order.
Try three practice positionsKey idea
Two cells restricted to the same two candidates reserve both digits, so neither candidate can appear elsewhere in any unit the pair shares.
See the move, step by step
Inspect box 7 and column 1, where R8C1 and R9C1 share the pair 2 and 3.
Step 1 of 4
Inspect the most restricted cells
In box 7 and column 1, compare the candidate lists near the bottom-left corner. Two cells are more restricted than their neighbors.
Step 2 of 4
Recognize the matching pair
R8C1 and R9C1 both contain exactly 2 and 3. One cell will become 2 and the other 3; the order is unknown, but the two digits are locked into these cells.
Step 3 of 4
Remove 2 and 3 from shared peers
Because the pair uses both digits, R7C1 cannot contain 3 and R9C3 cannot contain 2. These cells share column 1 or box 7 with the complete pair.
Step 4 of 4
Read the result of the eliminations
R7C1 is left with only 9, so the pair immediately creates a naked single. R9C3 is reduced to 1 or 5, while the original 2 and 3 pair remains unresolved.
Try three practice positions
Make one deduction in each position. All pencil marks come from the displayed grid. These are short technique exercises, not full puzzle completions.
Progress lasts while this lesson is open. Start again to reset these three exercises.
0 of 3 correct
Exercise 1 of 3
Guided
Inspect this unit: row 3. Find the naked pair, then select another cell where you can remove 9.
Select a cell, then check your move. Use arrow keys to explore the board. The selected cell’s candidates are also shown below at a larger size.
Select a cell to inspect its candidates.
Try it on today's puzzle
Scan each row, column, and box for two cells with identical two-candidate lists. Confirm that both cells belong to the same unit before removing those digits from its other cells.
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