Classic Sudoku
Learn how to play Classic Sudoku with standard 9×9 grid rules. Master row, column, and 3×3 box logic to solve any puzzle from easy to expert.
Objective
Fill the entire 9×9 grid with numbers 1-9, ensuring each number appears exactly once in every row, column, and 3×3 box. Start with given numbers and use logic to deduce the rest.
Rules
Row Rule
Each horizontal row must contain all digits from 1 to 9 without repetition. No number can appear twice in the same row.
Column Rule
Each vertical column must contain all digits from 1 to 9 without repetition. No number can appear twice in the same column.
Box Rule
Each 3×3 box (also called region or block) must contain all digits from 1 to 9 without repetition. The grid is divided into nine 3×3 boxes.
Solving Tips
- 1.
Start with the easiest cells: Look for rows, columns, or boxes that already have many numbers filled in.
- 2.
Use the process of elimination: If eight of nine numbers are present in a row, column, or box, the missing number is easy to find.
- 3.
Look for naked singles: Find cells where only one number is possible based on row, column, and box constraints.
- 4.
Use pencil marks: Note possible numbers in cells to help track your options and spot patterns.
Printable Classic Sudoku
Download today's free printable Classic Sudoku puzzle. The traditional 9x9 grid — fill every row, column, and 3x3 box with digits 1-9.
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