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Sudoku

4×4 for little kids, 6×6, then easy 9×9 — always one unique solution. Answer key stays off the paper.

Example

2563413255316631524346542

🔒 The answer is never printed — it shows in the app (and via the page's QR code).

How to play

  1. Fill every empty square so each row, each column and each box has every number exactly once.
  2. Start with rows, columns or boxes that are almost full. Every puzzle has exactly one answer, so no guessing needed.
  3. Check your answer in the app.

How it works

Procedurally generated, then dug so every grid has exactly one solution — a real sudoku, not a guessing game.

What you can set

Age dial (1–20): 1–6: 4×4 grid · 7–13: 6×6 · 14+: 9×9. More blanks as it climbs.

Build a page