Welcome to Sudoku!

Sudoku is a logic-based number placement puzzle. The objective is incredibly simple, yet the logic required to solve advanced puzzles can be remarkably complex.

The Golden Rule

To solve a Sudoku, you must fill a 9×9 grid with digits so that every column, every row, and every 3×3 subgrid (also called a "box" or "block") contains all of the digits from 1 to 9.

This means you can never have the same number twice in any:

• Horizontal Row
• Vertical Column
• 3x3 Box

How to Start: Cross-Hatching

The easiest way to start solving a Sudoku is a technique called Cross-Hatching. This involves focusing on a single number (let's say, the number 5) and scanning the grid to see where it *cannot* go.

Because the number 5 can only appear once per row, column, and box, you can use existing 5s to eliminate empty cells in nearby boxes. If you eliminate all empty cells in a box except for one, congratulations—you've found where the 5 must go!

Try It Yourself!

Below is a very simple puzzle designed to test your understanding of the basic rules. Scroll down to the interactive board and try to fill in the missing numbers. Remember: no guessing is required! Every single number can be deduced logically.