Lesson 8 · Intermediate technique
Naked Pairs
Lock two matching candidates into two cells and remove them from the rest of the unit.
See the logic move
Use Next to reveal each reason. On the final step, tap the highlighted cell to complete the move yourself.
Step 1 of 3
Focus
row 1, column 1 and row 1, column 4 reserve candidates 5, 6 in row 1.
Select an empty cell to see its legal candidates and why the other digits are blocked.
- 1
row 1, column 1 and row 1, column 4 reserve candidates 5, 6 in row 1.
- 2
Inspect R1C1, R1C4 and then check its row, column, and 3x3 box.
What the board is showing
Explain it simply
Two cells share the same two numbers. Those numbers belong to the pair, even before we know their order.
Step by step
- Find two cells with the same two candidates.
- Confirm they share one unit.
- Reserve those candidates for the pair.
- Remove them from other cells in that unit.
From demonstration to independent solving
Prove the move yourself
What you should be able to do
Prove that two digits are reserved for two cells in one unit and remove those digits only from the unit's other cells.
Read the exact board evidence
Suppose R1C1 and R1C4 each contain exactly {5,6}. Row 1 must place both 5 and 6 somewhere, and those two cells are their only reserved locations. Any 5 or 6 note in another row-1 cell can therefore be removed.
When the logic is strong enough
Both cells must share a row, column or box; together they must contain exactly the same two digits. Two overlapping candidate lists with extra digits do not form a Naked Pair.
Train the pattern without guessing
Search one unit at a time for two identical two-digit note sets. Before eliminating anything, name the shared unit and verify that neither pair cell contains a third candidate.
Quick check: Can candidates 5 and 6 be removed from the two pair cells themselves?
No. Keep them in the pair and remove them only from other cells in the unit.
Turn logic into skill