View the example grid
If two digits can appear only in the same two cells of an area, they form a Hidden Pair. Other candidates can be removed from those two cells.
An example from the app
In row 7, the digits 3, 8 occur as candidates only in the 2 highlighted cells C7, H7. Those cells also contain other notes.
Those 2 digits need exactly those 2 cells. The extra candidates in those cells cannot be true. The removals happen inside the highlighted group.
These notes are therefore ruled out: H7: 7, 9.
The image shows the candidates relevant to this step. A note being hidden does not mean it has been logically eliminated.
Practice the next step
This time the eliminations are inside the reserved cells, which is the key difference from a Naked Pair.
In the app, follow the reasoning in the matching lesson and try a task yourself. With a new puzzle, always start from its actual candidate state.
Questions about Hidden Pair
How do I recognize a Hidden Pair?
Two digits can occur only in the same two cells of an area. Those cells may also have other candidates.
Which notes can I remove?
Other candidates within the two reserved cells. Keep the two reserved digits.
Can a Hidden Pair occur in a box?
Yes. Examine a row, column or box. Within that area, the two digits must be restricted to the same two cells.
How does it differ from Naked Pair?
Hidden Pair starts with two digits and their positions. Naked Pair starts with two cells containing exactly the same candidate pair.
Why inspect the other cells too?
An extra position for either digit can invalidate the restriction. Looking only at the proposed pair is not enough.
Keep practicing in Unisu
Download Unisu for iPhone or Android. Solve a puzzle or work through a guided lesson on the technique.
