Sudoku

Fill every row, column and 3×3 box with the numbers 1–9 without repeating a number. Choose Easy, Medium or Hard, pencil in possibilities, and pick up your saved puzzle whenever you like.

Your progress is saved in this browser.

How to play

1. Fill every empty cell so each row, each column and each 3×3 box contains the numbers 1 to 9 exactly once.
2. Choose Easy, Medium or Hard. Harder puzzles start with fewer given numbers (44, 36 or 28 clues) and every puzzle has exactly one solution.
3. Tap a cell, then use the number pad or your keyboard. Turn on pencil notes to mark possible numbers, and conflicts are highlighted as you go.
4. Undo up to 100 steps. Your puzzle is saved in this browser, and a new puzzle replaces it only after you confirm.

Questions

Does every Sudoku puzzle have a single solution?

Yes. Puzzles are generated so that exactly one filling satisfies every row, column and box, so you never need to guess.

What is the difference between Easy, Medium and Hard?

Difficulty sets how many numbers are given at the start: about 44 on Easy, 36 on Medium and 28 on Hard. Fewer clues means more deduction.

Can I use pencil notes in Sudoku?

Yes. Switch on pencil mode to jot candidate numbers in a cell, and erase or undo them at any time.

Strategy guide

Sudoku Solving Techniques, Easy to Hard — Sudoku solving techniques from easy to hard: scanning, naked singles, hidden singles, pairs and pointing — with how to use pencil notes to find them.

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