How to play Sudoku

Sudoku is a number puzzle, but you do not need to be good at math — there is no adding at all. It is about logic and patience. Calm Sudoku uses big numbers, no timer, and puzzles that can always be solved step by step.

The goal

The board is a 9 × 9 grid divided into nine 3 × 3 boxes. Fill every empty square so that:

• each row has the numbers 1 to 9 once,
• each column has the numbers 1 to 9 once, and
• each 3 × 3 box has the numbers 1 to 9 once.

Some numbers are given at the start. Every Calm Sudoku puzzle has exactly one answer.

Filling in numbers

• Tap a square, then tap a number at the bottom of the screen.
• Tap Erase to clear a square.
• A red number does not fit — the same number is already in that row, column or box. You can change it any time. If you prefer to find mistakes yourself, red numbers can be turned off.

Using notes

Turn on Notes to write small reminder numbers in a square — the numbers that could still go there. The button has a yellow border while notes are on. Tap Notes again to go back to normal numbers.

A simple way to start

1. Pick a number, say 5.
2. Look at each box that does not have a 5 yet.
3. Check which squares in that box are blocked by a 5 in the same row or column.
4. If only one square is left, the 5 goes there.

Repeat with other numbers and you will be surprised how far you get.

Levels and help

• Choose Easy or Medium.
• Hint fills in one square and tells you why it must be that number.
• Undo takes back any move, and your puzzle saves itself.

Play Sudoku now

Want to get faster? Read our Sudoku tips.