A man met his tailor in the street and stopped him.
"I quite forgot to pay for the suit which I have on now," he said. "Why didn"t you remind me?"
"I never ask a gentleman for money," the tailor replied.
"Then what do you do if he doesn"t pay?"
"Well, after some time I no longer think he is a gentleman and then I ask him."
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.