A drummer, sick of all the drummer jokes, decides to change his instrument. After some thought, he decides on the accordion.
So he goes to the music store and says to the owner, "I"d like to look at the accordions, please."
The owner gestures to a shelf in the corner and says, "All our accordions are over there."
After browsing, the drummer says, "I think I"d like the big red one in the corner."
The store owner looks at him and says, "You"re a drummer, aren"t you?"
The drummer, crestfallen, says, "How did you know?"
The store owner says, "That "big red accordion" is the radiator."
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.