Beginner technique

Hidden Singles

Spot the only place a number can go inside a row, column, or 3x3 box.

What it means

A Hidden Single is different from a Naked Single: the cell may have several candidates, but one number has only one possible home in the unit.

How to use it

  1. Pick a row, column, or box.
  2. Choose one missing number.
  3. Mark every place that number is blocked; the remaining place is the move.

Practice this lesson

Read the full worked example, then open a live puzzle and look for the same pattern.

Full examplePractice Sudoku