LEVEL 5
Naked Quad
Four cells collectively contain only four candidates.
How to find it
- Combine candidate sets across four cells in one house.
- Confirm the union contains exactly four digits.
- Remove those digits from the remaining cells.
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 Quad training
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