Learn the puzzle
Rules of Sudoku
Sudoku is a placement puzzle built on elimination. Complete the nine-by-nine grid so each digit from 1 through 9 appears once in every row, column, and outlined box.
The objective
Complete the grid without repeating 1–9 in any row, column, or box.
01 · Sudoku
Treat the given digits as fixed clues.
Starting digits cannot be changed. Each clue removes that digit as a possibility from the rest of its row, column, and three-by-three box.
02 · Sudoku
Use 1 through 9 once in every row.
A completed horizontal row contains each digit exactly once. Scan for a digit that has only one legal square left in a row.
03 · Sudoku
Use 1 through 9 once in every column.
Vertical columns follow the same rule. A placement must satisfy its row and column at the same time.
04 · Sudoku
Use 1 through 9 once in every 3 × 3 box.
The bold outlines divide the board into nine boxes. Each box independently contains all nine digits without repetition.
05 · Sudoku
Use notes, then validate the solution.
Notes record candidates inside a square. Remove candidates as peers are solved; Check puzzle validates your entries, while Reveal ends the solve without a normal completion.
Quick reference
Four rules to remember
- 01 Rows Each row contains every digit 1–9 once.
- 02 Columns Each column contains every digit 1–9 once.
- 03 Boxes Each 3 × 3 region contains every digit 1–9 once.
- 04 Candidates Use notes to track possibilities before committing.
One shared puzzle each day
The puzzle remains hidden until you start, then the timer begins. Progress is saved so you can return later.
Ready for today’s puzzle?
Put the rules into practice.
Start today’s board or resume your saved progress.