Genius Academy / Level 3

LEVEL 3

Locked Candidates

Candidates confined to one line inside a box eliminate that digit elsewhere on the line.

How to find it

  1. Inspect one digit’s candidates within a 3×3 box.
  2. Find candidates that all share a row or column.
  3. Remove that digit from the rest of the same row or column outside the box.

Logical demonstration

The violet cells represent the pattern; the gold cell represents the resulting placement or elimination. Verify every highlighted candidate belongs to the required houses before acting.

Common mistakes

  • Using cells that do not share the required row, column, box or peer relationship.
  • Removing a candidate before confirming every occurrence in the pattern.
  • Confusing a possible pattern with a completed logical proof.

Practise the technique

Open a real puzzle, keep candidate notes accurate and ask Genius Coach to identify the next supported logical move.

Practise on a puzzle