Fill the grid in Sudoku
Sudoku is the world's favourite number puzzle. You're given a 9×9 grid partly filled with digits; complete it so that every row, every column and every 3×3 box contains the numbers 1 through 9 exactly once. No arithmetic — just pure logic.
How to play
Sudoku in 4 steps
Pick a cell
Tap or click an empty square in the grid to select it.
Enter a number
Type 1–9 (or use the number pad) to place a digit. Press 0 / Backspace to clear it.
Follow the one rule
Each digit 1–9 must appear exactly once in every row, every column and every bold 3×3 box.
Complete the grid
Fill every cell correctly to solve the puzzle. Toggle notes to pencil in candidates while you think.
Controls
- Click / Tap
- Select a cell
- 1–9
- Place a digit (or a note in notes mode)
- 0 / Backspace
- Clear the selected cell
- N
- Toggle pencil-notes mode
- R
- New puzzle
Strategy
Tips to play better
Hunt for forced cells
Scan rows, columns and boxes for a square where only one digit can legally fit. Those "naked singles" are free progress.
Use pencil notes
Jot the possible candidates into empty cells. When a candidate appears only once in a unit, it must go there.
Cross-hatch the boxes
For each digit, sweep across rows and columns to see which cells in a box it can't occupy — often only one remains.
Never guess
A proper Sudoku is always solvable by logic alone. If you're stuck, look for a new pattern rather than guessing.
About Sudoku
Although it feels Japanese, modern Sudoku was designed by American Howard Garns in 1979 (as "Number Place") and only became a worldwide phenomenon after Japanese publisher Nikoli popularised it and named it Sudoku — short for a phrase meaning "the digits must be single". A 2004 appearance in a British newspaper sparked the global boom.
Sudoku is pure deductive logic: despite the numbers, no arithmetic is involved, and a well-formed puzzle has exactly one solution reachable by reasoning. The number of valid completed grids is famously enormous — over 6.6 sextillion — which is why no two puzzles ever feel quite the same.
This Unicode edition generates a fresh, guaranteed-unique puzzle every time, with four difficulty levels set by how many digits you start with. Crisp numerals, a pencil-notes mode and an optional mistake highlight keep it friendly, and your best solve time per difficulty is saved locally.
FAQ
Sudoku questions
Do I need to be good at maths?
Does every puzzle have one solution?
What are pencil notes?
How are the difficulties different?
Is my time saved?
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