# Sudoku Rules

Sudoku is a logic puzzle that involves filling a 9×9 grid with numbers from 1 to 9. The grid is divided into 9 blocks of 3×3 cells, which must be filled using the rules:

Each digit must appear only once in each row.
Each digit must appear only once in each column.
Each digit must appear only once in each 3×3 block.

## Sudoku Strategy

There are several strategies and approaches to solving Sudoku, but in general they are all based on logic and a systematic approach. Let’s look at some of them:

Start with 3×3 blocks. Examine each block individually and determine which numbers are already present in the block. Fill in all the cells where the numbers can only be one.

Use “chains.” Find two cells where there can only be two digits, and determine which digit is in each cell. Then find the cell that is at the intersection of those two cells and determine which digit should be in that cell. Continue doing this until you are able to fill all the cells.

Examine each row and column separately. Determine which digits are already in each row and column, and fill in the cells where the digits can only be one.

Use the brute-force method. If you get stuck and can’t find the next step, start going through the numbers in the cell until you find the correct one.

It is important to understand that solving Sudoku requires not only logic, but also patience and persistence. The first couple of sudoku may take a long time, but as you practice, you’ll start to notice patterns and solve them faster and faster.

## Difficulty Mode

On our site you can choose from several difficulty levels: EASY, MEDIUM, HARD, VERY HARD. You can use the hints. Right below the playing field there are ONE STEP and ALL buttons. When you press them, they show one or all numbers respectively.