Sudoku rules, tips and solving techniques
Start with the rules, learn to read candidates, then practise solving techniques with worked examples and short exercises.
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Subscribe by RSS ↗Mini Sudoku · 4×4
Play free 4×4 mini Sudoku online. Learn with numbers 1–4, simple 2×2 boxes, hints and new beginner puzzles.
Killer Sudoku
Classic Sudoku rules, plus one twist: each dashed cage adds up to its small number. No repeated digits inside a cage.
Your first puzzle
Understand the rules and build reliable notes.
Sudoku for beginners: one rule is enough
No arithmetic and no guessing. Once you understand rows, columns and boxes, you are ready.
→Beginner · 3 minSudoku pencil marks: how to write and update candidates
Learn what the small numbers mean, how to find every legal candidate, and when a note can safely be removed.
→Find the next number
Two ways to prove that a digit is certain.
When singles run out
Remove candidates, then look for singles again.
Naked pairs in Sudoku: two cells that eliminate two digits
See exactly when two matching candidate sets form a naked pair, where you can erase their digits, and when the pattern does not apply.
→Intermediate · 3 minLocked candidates: pointing pairs and box-line reduction
When a digit is confined to one line inside a box, use that overlap to remove candidates. Learn both directions with a concrete example.
→Practice · 3 minStuck on Sudoku? A step-by-step checklist before guessing
Check mistakes, repair notes and scan the simplest patterns in a useful order. Know when a hint is helping and when it is only revealing an answer.
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