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Quick answer
Sudoku is a free number-placement logic puzzle that plays instantly in your browser on phones, tablets and computers, with no download, sign-up or ads. Fill the 9×9 grid so every row, column and 3×3 box holds the digits 1 to 9 once.
Sudoku at a glance
What it is
Number-placement logic puzzle
This page
Easy level: Naked singles only
Goal
Fill the 9×9 grid so every row, column and 3×3 box holds the digits 1 to 9 once
Modes
Easy, Medium, Hard and Expert, graded by the hardest solving technique needed; every puzzle has exactly one solution
Controls
Tap a cell and a number, or type 1-9; notes mode, auto notes, mistake highlighting, hints, undo
Players
1
Price
Free, no ads, no sign-up, no download
Works on
Phones, tablets and computers, in any modern browser
Fill the grid so every row, column and 3×3 box holds the digits 1 to 9 once each. That is the whole rule: no maths, no guessing, just logic.
How easy puzzles work
Easy puzzles start with about 38 digits already in place, and at every point there is at least one cell where only one digit can fit. This is called a naked single. To find one, pick an empty cell and cross off every digit already in its row, column and box. If only one digit is left, that is the answer.
Each digit you place rules out more options elsewhere, so the puzzle keeps opening up as you go.
Tips for your first games
Scan the busiest areas first. Rows, columns and boxes with many digits already filled leave the fewest options for the cells that remain.
Use the number pad counts. The small number under each digit shows how many are still to place. A digit with only one or two left is often easy to finish.
Tap a digit in the grid to highlight every copy of it. The gaps in the pattern show where that digit can still go.
Try notes when you are unsure. Switch Notes on to pencil in small candidates instead of committing to a digit.
When easy puzzles feel automatic, move on to Medium Sudoku, which needs one more technique.
How to play Sudoku
1
Know the goal
Fill every empty cell so that each row, each column and each 3×3 box contains the digits 1 to 9 exactly once.
2
Pick a cell
Tap or click a cell, then tap a digit on the number pad or type it on your keyboard.
3
Look for the only option
In an easy puzzle there is always a cell where only one digit can go. Check its row, column and box to find it.
4
Use hints if you get stuck
Hint highlights a cell you can fill next and explains why. Press Fill to place the digit.
The hardest level. Each puzzle needs an X-Wing, XY-Wing or Swordfish, and still never a guess.
Frequently asked questions
What makes a Sudoku easy?
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Easy puzzles here start with about 38 of the 81 digits filled in, and every step can be found with the simplest technique, a naked single, where only one digit fits a cell.
Does every puzzle have one solution?
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Yes. Every puzzle is checked by a solver that uses only logical steps, which proves the solution is unique. You never need to guess.
What does Show mistakes do?
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When it is on, a digit that does not match the solution turns red straight away. When it is off, only digits that clash with another in the same row, column or box are marked.
Is my game saved?
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Yes. Your progress is saved in your browser, so you can close the page and pick up the same puzzle later. Your best time for each difficulty is saved too.
Can I share a puzzle?
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Yes. The address bar holds the puzzle's code, so anyone who opens the same link gets the same puzzle.
Fancy a different puzzle?
Minesweeper is logic of another kind: read the numbers and clear the field without opening a mine.