Difficulty
Medium
Sudoku technique guide
Hidden Pair
When the easy moves slow down, one clear pattern can make the next step feel possible again. Hidden Pair helps you spot what the grid is already telling you.
By the end, you will know what to notice, how the idea works and when it is worth using.
At a glance
Technique family
Hidden subsets
Purpose
Removes candidates
Typical puzzle stage
Middle
Frequency
Occasional
Prerequisites
Hidden Singles and candidate marks
Why this technique matters
Hidden Pairs teach a different kind of focus: two digits matter because they have only two possible homes, even when those cells contain extra notes.
The idea in plain English
A Hidden Pair occurs when two digits can appear in only the same two cells of one unit. Other candidates in those two cells can be removed.
How to recognise it
Start with digits, not cells. You are looking for two missing digits that share exactly the same two possible locations.
Pause when you see this shape. You do not have to force it; just check whether the pattern is complete.
How the logic unfolds
Think of this as a short conversation with the grid. Take one check at a time, and let each answer tell you what to inspect next.
Start by. Choose a row, column or box and list its missing digits.
Then. Find two digits that each appear as candidates in the same two cells only.
Next. Confirm neither digit appears in another cell in that unit.
Finally. Keep the pair digits in those cells and remove their extra candidates.
When it usually appears
Use it when a unit has no Hidden Single but a few digits have very limited candidate positions.
Common traps
These are easy places to get turned around. They are useful checks, not signs that you are doing badly.
- Removing the pair digits rather than the extra candidates.
- Accepting two cells that match while one of the key digits also appears elsewhere in the unit.
Frequently asked questions
How is this different from a Naked Pair?
A Naked Pair is defined by two cells; a Hidden Pair is defined by two digits with two locations.
Can the pair cells have extra candidates at first?
Yes. Removing those extras is the point of the technique.
Quick takeaway
- A Hidden Pair belongs to the hidden subsets family.
- Its purpose is to remove candidates.
- Look for a complete pattern, not one that only nearly fits.
- It is most useful middle.
- Once you make the deduction, return to the simpler scans.