Naked Pair
Two squares show the same two notes. Together they reserve both digits for themselves.
What it is
Think of two reserved seats. If two squares in one row, column or box show exactly the same two notes, those two digits must fill those two squares in some order. You do not need to know which digit goes where. The important part is that neither digit can appear anywhere else in that unit.
How to spot it
Stay in one row, column or box. Look for a square with exactly two notes, then find a second square with the very same two notes. Ignore pairs that are only almost equal: 3/9 and 3/9 make a pair; 3/9 and 3/9/5 do not. Then cross those two digits out of the other squares in that unit.
Worked example
One observation at a time: find the matching pair, then see what it frees elsewhere in the unit.
Step 1 of 4: Look at one highlighted unit
Stay in this one row. Three empty squares carry the notes that matter.
Why it matters
A Naked Pair does not place a digit right away. It clears two notes from elsewhere, and that often reveals the next single. It is the simple starting point for larger pairs, triples and quads.
Practise now
Solve a puzzle where this technique decides the game
Frequently asked questions
Must the two cells be next to each other?
No. They only need to share a unit — the same row, the same column or the same box. They can sit at opposite ends of a row.
What if a third cell has the same two candidates?
Then something has gone wrong: three cells cannot share two digits. Re-check your pencil marks, because one of them is almost certainly incorrect.
Does a naked pair let me place a digit?
Not directly. It removes candidates elsewhere, and those removals are what create the singles you can place.
Put it to use
Where you will meet it
Medium grids are where this move starts to matter: the obvious cells run out and the pattern takes over.
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