Naked Pairs
Rated 3.0 on the technique scale · Two cells, two digits.
If two cells in the same unit can only hold the same two digits, those digits are locked into those cells — no other cell in the unit can use them.
Naked triples extend the same idea to three cells and three digits, and are worth 3.6 points. The practical difficulty is spotting them: look for cells with the same small candidate set.
A good habit is to scan for pairs immediately after each placement, because a new single often creates a pair next to it.
Naked Pair — These two cells can only hold 2 and 6, so no other cell in the row 6 can use them.
Practice it: naked pairs shows up most often in medium and hard puzzles. Browse those levels →
How the rating uses it
When a puzzle cannot be finished with easier techniques, the solver applies Naked Pairs and adds 3.0 to the puzzle's score. The hardest technique a puzzle needs decides its level, and puzzles with 26 clues or fewer move up one level.