Killer Sudoku

If you're getting a little bored with standard Sudoku why not give Killer Sudoku a go.

It's a more difficult version of Sudoku. It's the same as Sudoku in that the boxes must be filled in with all the numbers 1 to 9. But instead of seeing some starter clues where some cells are completed for you, in killer sudoku areas of the grid are "caged". Each cage contains a single number which is the sum of all the solutions in that shape. You have to use this information to work out what the numbers go in each box.