How to play Sudoku

Fill every row, column and thick-bordered box with 1–9.

Play dailyPlay practice

Make your first move

Select an empty cell, then type a number or use the number buttons.

Select a cell, then type 1–9 or tap a number. Arrow keys move between cells; Backspace, Delete or 0 erases. Use Notes for pencil marks and Erase to clear. Red numbers conflict with another number in a row, column or box. Hints reveal a cell and cost 15 points. Each generated puzzle has one solution.

A quick example

If a row already contains 1–8, its last cell must be 9.

Common mistake

Grey starting numbers cannot change. Notes are pencil marks, not answers.

Strategy to try

  1. Scan a nearly complete row, column or box. For an empty cell, rule out digits already present in all three groups. If only one digit remains, you have a single.
  2. A hidden single is a digit that fits in only one cell of a row, column or box, even when that cell has several candidates. Use Notes to keep candidate digits separate from answers.
  3. Choose Easy, Medium or Hard and press Start practice. These are approximate generator settings, not guarantees about your experience. Daily puzzles keep the same shared board. Hints cost 15 score points; deduction hints explain why a digit fits, while answer checks and reveals are labelled.

Daily play and practice

The daily board changes at midnight UTC. Your first completed daily score is saved in this browser. Practice starts a separate round. There is no account or subscription required; JavaScript is needed to play. Progress is device-local and clearing browser data removes it.

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