Naked Single Sudoku: Forced Move Guide
Learn naked single Sudoku with a quick definition, step-by-step candidate checks, common mistakes, and practice links for solving without guessing.
Try one easy puzzle before you read another guide
The fastest way to learn Sudoku is to play an easy grid right away, then come back to the article when you get stuck.
Print an Easy Puzzle →Naked single Sudoku means one empty cell has exactly one legal number left. If every other digit is blocked by the row, column, or 3×3 box, that final candidate is forced.
This is the beginner technique to use before guessing. Open Pure Sudoku, turn on notes when the puzzle gets crowded, and practice finding the cells that have only one candidate left.
Beginner Sudoku move Start a fresh Sudoku game, use notes when needed, and look for cells with one remaining candidate.Practice naked singles on a real board
What Is a Naked Single in Sudoku?
A naked single is a cell whose candidate list has been reduced to one number. The answer is visible from the cell itself, not from comparing every possible place for a digit across a row, column, or box.
Example: if a square can only be 7, then 7 must go there. No advanced pattern is involved. The row, column, and box have already eliminated every other digit.
| Question | Naked single answer |
|---|---|
| Where does the logic come from? | One cell has one remaining candidate. |
| Best time to use it | After scanning or updating pencil marks. |
| Difficulty level | Beginner, but it still appears in harder puzzles. |
| Main risk | Old notes can hide the forced move. |
How to Find Naked Singles Step by Step
Naked single scan routine
Pick one empty cell
Start with a cell in a crowded row, column, or box. The more filled numbers around it, the faster candidates disappear.
Check the row
Remove every digit already used in that row from the cell’s candidate list.
Check the column
Remove every digit already used in that column.
Check the 3x3 box
Remove every digit already used in the box. If one digit remains, place it.
Rescan after the placement
A solved cell can create another naked single nearby, so immediately recheck the same row, column, and box.
If notes feel messy, review how to use notes in Sudoku before moving into harder strategy pages.
Naked Single Sudoku Example
Imagine an empty cell in row 4, column 6. The row blocks 1, 2, 3, 5, 8, and 9. The column blocks 4 and 6. The box blocks 7. After those checks, every digit from 1 to 9 is blocked except one legal answer.
That is the point of the technique: you are asking, what can this exact cell be? Once only one number survives, the placement is forced.
Practice tip
Use Pure Sudoku as a free Sudoku browser game and pause after each placement. Naked singles often arrive in small chains when notes are kept clean.
Naked Single vs Hidden Single
Naked singles and hidden singles both produce one correct placement, but they answer different questions.
| Technique | Question to ask | What you see |
|---|---|---|
| Naked single | What can this cell be? | One cell has one candidate left. |
| Hidden single | Where can this digit go? | One digit has one possible cell in a row, column, or box. |
For the companion technique, read Hidden Single Sudoku.
Common Mistakes That Hide Naked Singles
If you place a number but do not remove it from nearby candidates, the naked single may already be there while your notes still show extra options. Beginners often check row and column only. A candidate is legal only when the 3×3 box also allows it. If a puzzle feels stuck, slow down and rescan the most restricted cells before trying a guess.Outdated notes
Skipping the box
Guessing too early
For broader error checks, use the common Sudoku mistakes guide.
A Simple Practice Plan
Use this routine on your next easy or medium puzzle:
- Scan the most filled boxes first.
- Add notes only where the answer is not obvious.
- After every placement, update notes in the connected row, column, and box.
- Look for cells that shrink to one candidate.
- When singles stop appearing, move to hidden singles or naked pairs.
Start a fresh Sudoku game and practice this routine before jumping to advanced patterns.
Naked Single Sudoku FAQ
- What is a naked single in Sudoku?
- A naked single is an empty cell with only one legal candidate left after checking its row, column, and 3×3 box.
- Is naked single the easiest Sudoku technique?
- Yes. It is usually one of the first logic techniques beginners learn because the answer is forced by direct elimination.
- What is the difference between a naked single and a hidden single?
- A naked single comes from one cell having one candidate left. A hidden single comes from one digit having only one possible position inside a row, column, or box.
- Do hard Sudoku puzzles still have naked singles?
- Yes. Hard puzzles can create naked singles after another technique removes candidates, so it is worth checking for them throughout the solve.
Keep practicing Use notes, solve one cell, then rescan the connected row, column, and box. Keep the next step focused on a real Sudoku board. Keep the next step focused on a real Sudoku board. Keep the next step focused on a real Sudoku board.Find the next forced move
Practice Next
Play Sudoku online
Easy Sudoku
Sudoku strategies
Naked singles are simple, but they are not trivial. They teach clean elimination, disciplined note updates, and the habit of checking forced moves before guessing.