Naked Pairs and Hidden Pairs are two faces of the same logical principle. Both prove that a pair of candidates must occupy a specific pair of cells, but they look completely different on the grid. Understanding how they relate - and how to spot each one - is one of the biggest leaps from beginner to intermediate Sudoku solving.
A Naked Pair is two cells in a row, column, or box that contain exactly the same two candidates and nothing else - for example two cells both showing only 4 and 7. A Hidden Pair is two candidates that appear only in the same two cells of a unit, even though those cells may contain other candidates as well - for example 4 and 7 appearing only in cells A and B of a row, while A might also list 1, 3, 9.
Both patterns prove that two specific cells must hold two specific values. With a Naked Pair, the cells already show that constraint visibly. With a Hidden Pair, the constraint is buried under extra candidates that need to be removed. The Hidden Pair literally becomes a Naked Pair once you eliminate the extras.
A Naked Pair eliminates its two candidates from every other cell in its shared unit. A Hidden Pair eliminates all other candidates from its two cells - the opposite direction. The first cleans up the unit; the second cleans up the pair itself. Both reduce the candidate landscape and unlock progress.
Always scan for Naked Pairs first. They are easier to spot because both cells visibly show the same two candidates. Hidden Pairs require methodical digit-by-digit scanning of each unit. Many beginners learn Naked Pairs quickly but need weeks of practice to see Hidden Pairs reliably.
Skipping Hidden Pairs leaves a huge category of progress unused. Hidden Pairs frequently appear in puzzles that look stuck after Naked Pair scanning is exhausted. The two techniques are partners, not alternatives - mastering both is what unlocks consistent intermediate solving.
They are the same logical principle viewed from opposite directions. A Naked Pair shows constraint directly; a Hidden Pair has the constraint hidden under other candidates.
Naked Pairs. Both cells visibly show the same two candidates - it is direct pattern recognition. Hidden Pairs require systematic digit-by-digit scanning.
Yes. They eliminate in opposite directions and frequently appear together. Skipping Hidden Pairs leaves easy progress on the table.
Yes. The same naked vs hidden distinction applies to triples and quads. Learn the pair version first; the larger sizes become natural extensions.
Both apply within a single row, column, or 3×3 box. Always scan all 27 units for each pattern.
They are visually buried. The cells holding the pair often look complex with multiple candidates, and the pattern only emerges when you focus on which two candidates appear in only the same two cells.
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