Killer Sudoku uses the same rules as conventional Sudoku in that you must use the numbers 1 to 9 with each number occurring once in each row, column and 3x3 box. In the case of Killer Sudoku the clues are in the form of a sum of the numbers in a cage (defined bya dotted line and of the same color).

For example, a cage with the total of 3 can only contain the numbers 1 and 2, a cage with a total of 4 can only contain 1 and 3 (since we cannot use the same number in an row, column or box). By using a combination of the rules we can work out the possible values for a cell.

The same Sudoku Strategies can also be applied to Killer Sudoku.