Lesson 6 · Beginner technique

Hidden Singles

Find the only cell in a row, column, or box that can hold a particular number.

Written and puzzle-tested by Chamara S. Kodikara · Last reviewed 3 August 2026

See the logic move

Use Next to reveal each reason. On the final step, tap the highlighted cell to complete the move yourself.

Step 1 of 3

Search for 7

Focus on row 4. Number 7 is still missing.

What the board is showing

Relevant cellsThese cells share the row, column, or box used by this step.Row 4

Explain it simply

The answer is hidden among several notes, but that number has only one home in the group.

Step by step

  1. Choose one row, column, or box.
  2. Pick a missing number.
  3. Mark every cell blocked for that number.
  4. Fill the one legal cell left.
Quick check: Can a Hidden Single cell still contain several candidate notes?

Yes. One candidate is special because it appears nowhere else in that unit.

Turn logic into skill

Practice this technique on a live board

Practice now