Suduko Rules

The rules of Suduko are very simple, and whether you're solving an easy or a very difficult puzzle the rules are the same.

To complete a Suduko you must fill the empty boxes of the grid with the numbers 1 to 9. A puzzle is correct if when all the boxes have numers in them, every row, every column and every 3 by 3 subgrid contain the number 1 to 9 in them once.