A young boy was playing with a ball in the street. He kicked it too hard, and it broke the window of a house and fell inside. A lady came to the window with the ball and shouted at the young boy, so he ran away, but he still wanted his ball back.
A few minutes later he returned and knocked at the door of the house, and when the lady answered it, he said, "My father"s going to come and fix your window very soon."
After a few more minutes a man came to the door with tools in his hand, so the lady let the boy take his ball away.
When the man finished fixing the window, he said to the lady, "That will cost you exactly ten dollars."
"But aren"t you the father of that young boy?" the woman asked, looking surprised.
"No," he answered, equally surprised. "Aren"t you his mother? "
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.
