Naked Pair
When two cells in a unit share the same two candidates.
Explanation
If two cells in one row, column, or box can only contain the same pair of digits, those digits are reserved for the pair and can be removed from the other cells in that unit.
Practice tip
Fill candidates first, then scan each unit for identical two-number notes.
Example steps
- Find two cells in one unit with exactly the same two candidates.
- Treat those two digits as reserved for the pair.
- Remove the pair candidates from the other cells in that unit.