Medium Used from medium puzzles up.
Hidden Pair
Two digits, the same two cells
Two digits that can only go in the same two cells of a unit will fill those two cells, one each.
Those cells are then taken: remove every other candidate from them.
The pair hides among other candidates, which makes it harder to see than a Naked Pair.
What to look for
Find two digits that, in one unit, appear in the same two cells and nowhere else.
Example
- The cells the technique relies on
- Cells where it removes candidates, struck out in red
Practise it
In the app, Learn › Hidden Pair sets exercises on real positions, then a full puzzle that needs this technique and nothing harder.