Hidden Pairs Technique in Sudoku
Two digits in a row, column, or 3×3 box that appear as pencil marks in only two cells lock those two cells. Erase all other candidate notes inside those two cells to unmask the pair.
How to Spot Hidden Pairs
Track Low-Frequency Digits
Look for numbers that have only 2 possible positions in a row, column, or block.
Match Cell Coordinates
If two numbers share the identical pair of candidate cells, they form a Hidden Pair.
Clear Other Candidates
Erase all other pencil mark numbers inside those two cells.
Frequently Asked Questions
What is a Hidden Pair in Sudoku?
A Hidden Pair occurs when two digits appear as candidates in only two cells of a row, column, or 3×3 box. Even if those two cells contain other candidate numbers, the two target digits MUST occupy those two cells. Therefore, all other candidate numbers can be safely erased from those two cells.
What is the difference between a Naked Pair and a Hidden Pair?
In a Naked Pair, two cells clearly show only those two digits (no extra noise), and you eliminate those digits from the rest of the house. In a Hidden Pair, the digits are 'hidden' by other candidates, and the elimination happens INSIDE the pair cells itself (pruning the extra noise candidates).
What is the easiest way to spot a Hidden Pair?
Rather than looking at cells, look at individual numbers. Scan a row, column, or box for any number that only has 2 candidate spots. If another number shares the EXACT same two candidate spots, you have found a Hidden Pair.
Looking for higher-order sets?
Explore Hidden Triples to see how the same logic expands to 3 numbers across 3 cells.