The Hidden Pair Technique in Sudoku
The Hidden Pair is the twin of the Naked Pair, and it is the technique most beginners overlook. When two digits can only go in the same two cells of a unit, those cells must hold exactly those two digits — so every other candidate in them can be erased.
How to use a Hidden Pair, step by step
- Work from full pencil marks.
- In a row, column or box, find two digits that each appear as candidates in only the same two cells.
- Those two cells must take those two digits between them.
- Erase every other candidate from those two cells.
- You have effectively created a Naked Pair — now look for the singles it opens up.
What is a Hidden Pair?
A Hidden Pair is two digits that, within one unit, can only be placed in the same two cells — even if those cells still show other candidates. Because the two digits have nowhere else to go, they claim those cells, and the extra candidates can be removed. It is the exact counterpart of the Naked Pair: one looks at what a cell can be, the other at where a digit can go.
How to spot a Hidden Pair
Scan a unit one digit at a time and note how many cells each digit can still go in. When two different digits are each restricted to the very same two cells, you have a Hidden Pair. Beginners miss these because the cells look “busy” with other candidates — the trick is to track digits, not cells. More in tips & strategy.
Hidden Pairs in Sudoku: FAQ
What is a Hidden Pair in Sudoku?
A Hidden Pair is two digits that can only be placed in the same two cells of a row, column or box. Those cells must take the two digits, so any other candidates in them can be erased.
How is a Hidden Pair different from a Naked Pair?
A Naked Pair is two cells showing only the same two candidates. A Hidden Pair is two digits restricted to the same two cells, where those cells may still display extra candidates that you then remove. They are mirror images of one idea.
How do you spot a Hidden Pair?
Track digits rather than cells: within a unit, look for two digits that each have only the same two possible cells. When you find them, erase all other candidates from those two cells.