How to Play Sudoku

Sudoku is one of the most loved relaxing puzzle games in the world. It uses numbers, but it is not a maths game: there is no adding or multiplying, only logic. If you can notice what is missing from a list, you can play Sudoku. This guide walks through the rules, a calm way to start, and the habits that make solving feel effortless.

The rules

A Sudoku grid has 81 squares arranged in nine rows, nine columns and nine 3×3 boxes. Some squares already contain numbers; these are called givens. Your job is to fill every empty square with a digit from 1 to 9 so that:

• Each row contains every digit from 1 to 9 exactly once.
• Each column contains every digit from 1 to 9 exactly once.
• Each 3×3 box contains every digit from 1 to 9 exactly once.

That is all. Every Quietgrid puzzle has exactly one correct solution, which means you never need to guess. Every number can be reached by reasoning.

Getting started

Begin by choosing a digit that already appears many times on the board. Suppose there are six 4s. Look at each 3×3 box that is missing a 4, and check which of its empty squares are blocked by a 4 in the same row or column. If only one square remains, place the 4. This method is called scanning, and it solves a surprising amount of every easy puzzle.

Next, look for rows, columns or boxes that are nearly full. If a row already has eight digits, the last one is obvious. If it has seven, check which two digits are missing and which of the two empty squares each can go in.

Using pencil notes

As puzzles get harder you will need to track possibilities. In Quietgrid, tap Notes or press N on your keyboard to switch into pencil mode. Now digits you enter appear small, as candidates. When you place a real number, Quietgrid automatically removes that digit from the notes of every related square, keeping your board tidy.

Controls in Quietgrid

• Tap a square, then tap a number on the pad (or type 1–9).
• Use arrow keys to move, Backspace to erase, Ctrl+Z to undo.
• The selected square's row, column and box are softly highlighted, along with every matching number.
• You have three hints per game. The mistake checker can be turned off for a purer challenge.
• Pause any time; the board blurs so you can step away without peeking.

Tips for a calmer solve

Never guess. If you feel stuck, it simply means there is a pattern you have not noticed yet. Step back and scan each digit again from 1 to 9.

Work where it is crowded. Boxes and lines with the most numbers give the most information.

Use the highlights. Tap a given number and Quietgrid highlights every copy of it. Gaps in the pattern often reveal where that digit belongs.

Take breaks. Sudoku is meant to be a pleasant pause in your day. Your game saves automatically, so you can come back later with fresh eyes — often the answer is suddenly obvious.

Choosing a difficulty

Easy puzzles can be solved by scanning alone. Medium puzzles reward pencil notes and singles. Hard puzzles introduce pairs and pointing techniques, and Expert puzzles may call for patterns like the X-Wing. Our strategy guides explain each one with plain language.

Make it a daily ritual

The best way to improve is a little every day. The free daily sudoku is the same for every player, so you can compare times with friends and build a streak. Ten quiet minutes with a cup of coffee is all it takes.