All Tutorials/How to Use Candidates

How to Use Candidates

beginner

Using pencil marks to track possibilities

Candidate notation (pencil marks) is essential for solving harder puzzles.

Understanding the Concept

Candidates are small numbers written in cells to show which digits are still possible.

Also called pencil marks, possibilities, or notes.

Write all possible numbers (1-9) that could go in each empty cell.

As you solve, remove candidates that become impossible.

When only one candidate remains in a cell, that's the answer.

Candidates help you spot patterns and apply advanced techniques.

Examples

Candidate Example

A cell might have candidates 2, 5, and 7, meaning only these numbers are possible there.

Pro Tips

  • Be systematic - fill in all candidates before solving
  • Update candidates immediately when placing a number
  • Look for cells with few candidates first
  • Use candidates to spot hidden patterns

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