How to Play Sudoku

What is Sudoku?

Sudoku is a logic-based number puzzle played on a 9x9 grid. The grid is divided into nine 3x3 boxes. Some cells are pre-filled with numbers (called "givens"), and your goal is to fill in the remaining cells following simple rules.

Grid Anatomy

A Sudoku grid has 9 rows, 9 columns, and 9 boxes. Rows run horizontally, columns run vertically. Boxes are 3x3 blocks of cells. In the example below, given numbers are bold; empty cells are for you to fill.

Key Terminology

Common terms in Sudoku:

• Row — 9 horizontal cells
• Column — 9 vertical cells
• Box — a 3x3 block
• Given — a pre-filled number at the start
• Candidate — a possible number for a cell

The Three Rules

1. Rows: Each row must contain the numbers 1 through 9, with no repetition.
2. Columns: Each column must contain the numbers 1 through 9, with no repetition.
3. Boxes: Each 3x3 box must contain the numbers 1 through 9, with no repetition.

Getting Started

• Scanning: Look across rows and down columns to find cells where only one number can go.
• Crosshatching: Focus on one box at a time. Check which numbers are missing and where they can be placed.
• Pencil Marks: Use the Draft/Note mode to write possible candidates in cells. This helps with harder puzzles.

Tips for Beginners

• Start with easier difficulty levels to learn patterns.
• Focus on boxes, rows, or columns that are almost complete.
• Use the pencil marks feature to track possible numbers.
• Look for numbers that appear frequently on the board.
• Don't guess! Sudoku is solvable purely through logic.

Advanced Techniques

As you progress to harder puzzles, you'll need more advanced techniques. Check out our techniques guide for strategies like Naked Pairs, X-Wing, and more.