What this puzzle trains
This dense layout rewards precise chain reasoning and consistent follow-through.
This Expert #021 starts with 30 clues, has a score of 437, and mainly asks you to use Naked Single / Hidden Single / Pointing / Naked Triple / Simple Chain.
Puzzle #021 appears early in this archive and is a good place to check your baseline accuracy.
Useful habits for this level
- Track chain logic with explicit reasoning.
- Return to Singles immediately after each major elimination.
After-solve notes
Individual puzzle pages are practice stops reached from the archive or strategy guides. After solving, keep these three notes so the next puzzle has a clear learning target.
- At the first stall, did you check "Track chain logic with explicit reasoning." before looking for Naked Single / Hidden Single / Pointing / Naked Triple / Simple Chain?
- If you used a hint, write one target cell, elimination, or condition in your own words.
- Choose whether to continue at this level or read the related technique guide before returning.