GETTING STARTED
Sudoku Rules: How to Play and Solve
The rules of Sudoku are simple: each digit from 1 to 9 appears exactly once in every row, column and 3×3 box. Learn how to use these constraints to solve a puzzle without guessing.
Updated · AE Book Studio
Sudoku rules: rows, columns and boxes
A digit can appear only once in a row, once in a column and once in a 3×3 box. Printed clues never change.
No arithmetic is involved. Nine is not stronger than two; they are simply distinct symbols.
Start the puzzle
Find a nearly complete row, column or box. Identify its missing digits and check possible positions against the other two directions.
Place only a certain value. Scan again after every entry because a new digit often creates another direct move.
Use candidates
When a cell accepts several values, note them lightly. Place a digit when only one remains. If a digit has one location in a unit, it can be placed even if that cell has other candidates.
Remove candidates made impossible by each placement so notes remain trustworthy.
Do not guess
A random trial may travel far before causing a contradiction. A sound puzzle has a logical path. When stuck, verify the rules and notes first.
With practice, your eye spots missing digits, intersections and pairs faster.
FAQ
Frequently asked questions
Do I need to be good at maths?
No. Sudoku is a game of logic and exclusion.
Can a digit repeat inside a box?
No. Each digit appears once in every box.
What should I do when stuck?
Scan by digit and verify candidates before adding a new technique.
What are the rules of Sudoku?
In a 9×9 Sudoku, each digit from 1 to 9 appears once in every row, every column and every 3×3 box.