Naked Singles - The Most Fundamental Sudoku Technique
A naked single is the simplest logical placement in sudoku. You inspect one empty cell, remove every digit that already appears in the same row, column, and 3x3 box, and discover that only one candidate remains. That remaining value is forced. No guesswork is involved, and no advanced pattern is needed.
If you are learning sudoku for the first time, naked singles are the right place to start. They appear constantly in Very Easy Sudoku and Easy Sudoku, and they continue to appear even in harder boards as follow-up placements after more advanced eliminations.
How to Find Naked Singles
- Pick an empty cell.
- List the digits already present in the same row, column, and box.
- Cross those digits off from 1 through 9.
- If only one digit is left, you found a naked single.
Example: if the row already contains 1, 2, 4, and 7, the column contains 3 and 8, and the box contains 5, then only 6 and 9 are missing overall. If 9 is blocked elsewhere in the same unit, 6 becomes the only legal value and must be placed.
Using Naked Singles to Solve Easy Sudoku
Most early sudoku puzzles can be solved almost entirely through naked singles and patient scanning. Start with the most constrained areas of the board: rows with many filled cells, columns with only a few gaps, or boxes that already contain six or seven numbers. Every naked single you place will often create another one nearby.
That is why good players solve in loops. Place one naked single, update the surrounding units, then rescan the board. This steady cycle builds accuracy and rhythm without ever needing to guess.
Tips
- Scan the most crowded row, column, or box first. More fixed digits mean fewer candidates.
- After every placement, immediately check neighbouring cells for fresh singles.
- If you stop finding them, switch to a digit-by-digit scan instead of staring at one area.
- When naked singles dry up, learn Hidden Singles next.
Frequently Asked Questions
What is a naked single in sudoku?
A naked single is a cell with only one legal candidate left after checking its row, column, and box.
Is naked singles a beginner technique?
Yes. It is the first technique most players learn and it powers the easiest puzzle levels.
Can you solve all sudoku with naked singles?
No. You can solve many simple boards that way, but harder puzzles need more tools.
What comes after naked singles?
Hidden singles are the natural next step because they teach you to scan units instead of isolated cells.
Next Steps
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Practice This Technique
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