About Sudoku
A Sudoku puzzle is a 9x9 grid, with some cells in the grid filled in with a number, “1” through “9”.
The challenge is to complete the grid by also filling every empty cell with a number, “1” through “9”, and follow these rules:
- A number may only be present once in each row
- A number may only be present once in each column
- A number may only be present once in each of the nine marked 3-by-3 boxes.
Every puzzle only has one solution.
Sudoku level 4 example
