Technique
When You Need an Naked Single
Naked singles are the most basic deduction in Sudoku and the technique every easy puzzle is built around. Filling one often creates more, so a single find can cascade through several cells.
At a glance
Naked Single at a Glance
- Technique
- Naked Single
- Difficulty level
- Beginner
- Also known as
- sole candidate, forced digit
- First needed on
- Easy puzzles
How to spot it
How to Spot an Naked Single
Pick an empty cell and list which digits already appear in its row, its column, and its box. If that list covers eight of the nine digits, the ninth is a naked single and belongs in that cell.
Common mistake
The Mistake Solvers Make
Confusing a naked single with a hidden single. A naked single is about one cell having one candidate. A hidden single is about one digit having one available cell within a unit — the cell may still have several candidates.
Practice
Practise This Technique
Easy puzzles are where the naked single first becomes necessary. Generate a free printable easy Sudoku PDF and work through a few.
More techniques
Other Sudoku Techniques
- Hidden Single — beginner
- Naked Pair — intermediate
- Pointing Pair — intermediate
- X-Wing — advanced
- Swordfish — advanced
FAQ
Naked Single — Frequently Asked Questions
What is an naked single in Sudoku?
A naked single is a cell where only one digit remains possible, because the other eight already appear in that cell's row, column, or 3×3 box. The digit is forced — no other value can legally go there.
How do you find an naked single?
Pick an empty cell and list which digits already appear in its row, its column, and its box. If that list covers eight of the nine digits, the ninth is a naked single and belongs in that cell.
Is the naked single a beginner or advanced technique?
It is a beginner technique. Naked singles are the most basic deduction in Sudoku and the technique every easy puzzle is built around. Filling one often creates more, so a single find can cascade through several cells.