Sudoku solving technique · Beginner
Hidden Single
A digit that has only one place left in a row, column or block.
What is a Hidden Single?
When a number can only fit in one cell within a row, column, or block, it must go there, even if that cell has other candidates too.
How to spot a Hidden Single
Pick a digit and work through the units one by one: where can this digit still go in this row, column or block? If only one cell is left, it goes there. The cell itself may still have other candidates, which is why a Hidden Single is easy to miss when you only look at single cells.
- Difficulty
- In Sudoku Pro, this technique belongs to the Beginner level.
- Learning path
- Technique 2 of 20 on the learning path
An example from the app
| Given 1 | Pattern (purple). Candidates 2, 3 | Candidates 3, 4 | Candidates 3, 4 |
| Given 4 | Empty | Given 1 | Given 2 |
| Empty | Given 1 | Empty | Empty |
| Empty | Given 4 | Given 2 | Given 1 |
Small digits are candidates. Crossed-out digits can be removed in this step.
- Pattern (purple)