A little boy comes home with his mother from a trip down town. Above his head he has a big bunch of balloons.
- Why do you need so many? - Asks his father. - Did not your mother and I teach you that you should save your money?
- I did not spend any! Its just that every time Mummy bought something the salesperson gave me a free balloon.
Sudoku is played on a square field 9 by 9 of cells. The field itself is divided into regions (3 by 3 squares).
The goal of Sudoku is to fill all the empty cells with numbers 1-9 (one digit per cell), using the following rules:
1. The number can appear only once in each row.
2. The number can appear only once in each column.
3. The number can appear only once in each district.
Simply put, the same number can appear only once in each row, column and region.