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Sudoku stats
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- Games played
- 1
- Highest score
- 0
- Players
- 1
- Time played
- 1m
How to play Sudoku
Fill the grid so every row, every column and every three-by-three box holds the numbers 1 to 9 exactly once. No math, no guessing - everything you need is already on the board.
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Pick a cell
Tap an empty cell, or move to one with the arrow keys. The cells printed in bold came with the puzzle and cannot be changed.
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Enter a number
Use the keypad under the board or just type 1 to 9. Erase clears the cell you are on.
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Make notes when you are not sure
Notes turns the keypad into pencil marks, so you can park two or three candidates in a cell and come back to it. Notes never count as answers.
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Watch your three mistakes
A number that clashes with one already on the board costs a life. Three and the board is over with no points, so it is worth reading a row twice.
Sudoku difficulty levels
Four tiers, switchable on this page at any time. Nothing is locked, and a harder board is worth more when you finish it.
- Easy
- 36 numbers are filled in for you. Most cells can be solved by looking at one row, column or box.
- Medium
- 30 given numbers. You will need to compare two or three lines before a cell gives itself up.
- Hard
- 26 given numbers, and some cells only fall once you have ruled out everything else.
- Expert
- 22 given numbers. Expect to use notes, and expect it to take a while. Every one of these is solvable without a single guess.
Sudoku tips
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Chase one number at a time
Pick 7, then look at every row, column and box that already has one. Often a box has exactly one cell left where a 7 can go, and you would never have seen it staring at the cell itself.
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Count what is missing, not what is there
A row with seven numbers in it is really a question about two empty cells. Say the two missing numbers out loud and check which one the column will not allow.
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Use notes before you need them
On hard and expert, pencil in candidates while the grid is still open. Starting your notes after you are stuck means doing the same scan twice.
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Never guess
Every puzzle here is checked by a solver before it is published, so there is always a next step you can prove. A guess that happens to be right teaches you nothing, and a guess that is wrong costs a life.
Sudoku questions
What happens when I run out of mistakes?
The board ends and scores nothing. The three strikes only count numbers that contradict something already visible on the grid, so you are never charged for a mistake you had no way to see.
Can I undo a number?
Select the cell and press Erase, or type over it. A cell you have already cleared costs nothing.
Is there more than one solution?
No. Every grid is generated with exactly one answer and tested for it, which is also what makes the no-guessing promise possible.
Do I need to be good at math?
Not at all. The numbers are only symbols - you could play the same puzzle with nine colors or nine letters. Nothing is ever added or multiplied.
Does the timer matter?
It affects your score but it never stops you. Finishing at double the normal time still scores about three quarters, and there is no penalty for putting a puzzle down and coming back.
Scoring, streaks and levels work the same way on every game and are explained on the about page.