View the example grid
A Naked Single is a cell with exactly one candidate remaining. Its row, column and box rule out every other digit.
An example from the app
The highlighted row is missing 3 and 5. Looking only at this row, either could go in its top-left empty cell.
Now check the column of that cell: it already contains 3. Only 5 fits the cell. The small 5 records this checked result — a Naked Single.
Practice the next step
The cell’s candidate list must be complete. Forgetting a note does not turn two possibilities into a single.
In the app, follow the reasoning in the matching lesson and try a task yourself. With a new puzzle, always start from its actual candidate state.
Questions about Naked Single
When is a cell a Naked Single?
When exactly one digit remains possible. Check the cell’s row, column and box together.
Is it the same as Hidden Single?
No. Naked Single examines a cell’s candidates. Hidden Single examines a digit’s possible positions within an area.
Does one visible note prove a Naked Single?
Only if the candidate list is complete and current. A forgotten possibility does not make the cell unique.
What should I check after placing it?
Update its row, column and box. The new digit can rule out further candidates there.
What if there is no Naked Single?
Look for Hidden Single or another suitable pattern. Having several possibilities is not a reason to guess one.
Keep practicing in Unisu
Download Unisu for iPhone or Android. Solve a puzzle or work through a guided lesson on the technique.
