Classic Killer Rules Articles

Sudoku Rules

Sudoku is a Japanese puzzle where you need to write numbers according to specific algorithms (so they don't repeat vertically, horizontally, or diagonally). In simple Sudoku, you need to fill in the missing numbers in 3x3 cells. Complex Sudoku can have more than three rows and three columns, up to 6x6, 9x9, or more cells.

In the classic Sudoku version, you have nine three-by-three blocks where you need to enter numbers from one to nine. The basic rules are as follows:

  • · Vertical numbers cannot be repeated.
  • · Horizontal numbers cannot be repeated.
  • · Numbers can only appear once in 3x3 squares.
Sudoku Rules Example 1 Sudoku Rules Example 2

The rules of classic Sudoku mean that some numbers are already fixed at the beginning. This makes it easier to analyze the grid and find the missing values. The number of empty cells and numbers depends on how challenging you want the puzzle to be. The higher the challenge level, the fewer cells are filled in (so you need to use specific techniques to quickly and accurately fill the entire grid).

Once you enter all the numbers into the fields, you're done. You can continue to the next one.

Sudoku Techniques

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