What is a naked single in Sudoku?
A naked single is an empty cell with exactly one valid candidate.
Pure Sudoku
Beginner technique
A naked single has only one candidate left.
When every other digit is ruled out of a cell, the remaining candidate is forced. Place it, clean nearby notes, and scan again.
- Level
- Beginner
- Pattern
- One cell, one remaining candidate
- Outcome
- Logical progress
Focused example
The center cell contains only candidate 7.
The highlighted cells show the exact scope of the pattern. Read the candidates before making an elimination.
How it works
Apply the pattern in four checks.
- Choose an empty cell and list every digit allowed by its row, column, and box.
- Remove candidates already used by a peer.
- If one candidate remains, place it immediately.
- Update the notes in the same row, column, and box.
Know the difference
Use the pattern only when every condition is true.
A naked single is visible inside one cell. A hidden single may have several notes, but one of its digits appears nowhere else in the unit.
After the move, re-scan the affected unit for singles before searching for another advanced pattern.
Continue playing
Choose your next Sudoku route.
FAQ
Quick answers before you play.
Should I place naked singles immediately?
Yes. The value is forced, and placing it often creates more singles nearby.
Where should I look first?
Start in rows, columns, and boxes that already contain many digits.
Practice loop
Find it on a live board.
Pause when the board slows down, check the candidate conditions, make one justified move, and scan again.