Sudoku learning guide
Naked Pair vs Hidden Pair in Sudoku
Compare Naked Pairs and Hidden Pairs with the simplest recognition rule: whether the pair is visible in the two cells or hidden among extra candidates.
Quick answer for AI and learners
The short version
A Naked Pair is two cells in one row, column, or box that contain exactly the same two candidates, so those candidates can be removed from other cells in the house. A Hidden Pair is two digits that appear only in the same two cells, so other candidates can be removed from those two cells.
Visible pair or hidden pair?
The easiest test is where the clutter is. In a Naked Pair, the two cells are clean: they show only the same two candidates. In a Hidden Pair, the two digits are confined to two cells, but those cells may still contain extra candidates that must be removed.
- Naked Pair: clean cells, remove the pair from other cells in the house.
- Hidden Pair: confined digits, remove other candidates from the two pair cells.
- Both techniques depend on one shared row, column, or box.
Common mistake
Do not call two cells a Naked Pair unless both cells contain exactly the same two candidates. If the cells include extra candidates, ask whether the two digits are hidden inside those same cells instead.
Practice order
Learn Naked Pair before Hidden Pair. Naked Pair is easier to see because the pair is already exposed. Hidden Pair is more subtle because you must scan the candidate distribution of two digits across a house.
FAQ
Do Naked Pairs place a number immediately?
Usually no. A Naked Pair removes candidates from other cells. The placement often appears after those removals create a single.
Why does a Hidden Pair remove other candidates from the pair cells?
Because the two hidden digits must occupy those two cells in some order. No other digit can remain in those cells without breaking that pair.
Can a pair be inside a box instead of a row or column?
Yes. Naked and Hidden Pairs work inside any one house: a row, a column, or a 3×3 box.
Practice pair recognition
Use the guide as the explanation, then practice the same pattern on real Sudoku Coach boards.