LEVEL 1
Naked Single
One empty cell has only one legal candidate.
How to find it
- List the digits already present in the cell’s row, column and box.
- Remove those digits from 1–9.
- If one candidate remains, place it.
Candidate-map demonstration
The violet cells mark the pattern and the gold cell marks the resulting placement or elimination. Treat this compact map as orientation; use the verified full puzzle below to practise the actual deduction.
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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.
VERIFIED PRACTICE
Naked Single training
Loading a mathematically verified puzzle state…