Hidden Single Walkthrough

A Hidden Single is a digit that can legally go in only one cell of a row, column, or box, even though that cell still shows other candidates. The digit is forced into that single spot.

Sudoku board with pencil-mark candidates before applying the Hidden Single technique — Before — candidates pencilled in. There is a Hidden Single in Row 2.

There is a Hidden Single in Row 2. Applying the Hidden Single places 1 digit (struck out in red below; any solved cells shown in green).

The same Sudoku board after the Hidden Single technique places 1 digit — After applying the Hidden Single.

Learn the Hidden Single technique →Practice it on a real puzzle →