Sudoku
About Sudoku
Sudoku is the world's favourite number-placement puzzle, free to play here in your browser. You are given a 9×9 grid partly filled with digits, and the goal is to complete it so that every row, every column and every 3×3 box contains the numbers 1 to 9 exactly once. Despite using numbers, Sudoku needs no arithmetic at all — it is pure logic. There is nothing to install and no account required.
How to play
- Study the grid and the digits already placed.
- Choose an empty cell and work out which number can legally go there.
- Make sure that number does not already appear in the same row, column or 3×3 box.
- Keep filling cells using logic until the whole grid is complete.
What it trains
Sudoku is a workout for logical reasoning, concentration and pattern recognition. Every move is a small deduction, and holding the constraints of rows, columns and boxes in mind at once builds working memory and mental discipline. Many people find a daily puzzle a calming, focused way to keep the mind agile.
Solving techniques
- Scan rows, columns and boxes for a digit that can only fit one place.
- Look for cells where only a single candidate number is possible.
- Pencil in candidates for tricky cells and eliminate them as you place digits.
- Work from the fullest rows, columns and boxes first — they have the fewest options.
Frequently asked questions
Do I need to be good at maths to play Sudoku?
No. Sudoku involves no arithmetic — the digits are just symbols. It is entirely a puzzle of logic and placement.
Is this Sudoku free?
Yes, it plays free in your browser with no sign-up or download.
Does every Sudoku have one solution?
A well-formed Sudoku has exactly one correct solution that can be reached by logic alone, without guessing.