The Kakuro needs both logic and arithmetic – just adding-up and subtraction, anyway.
The numbers in a Kakuro are like clues. Each is a total to a sum. You have to work out which numbers add up to the total to fill the blank squares. Sounds easy, but each answer has to fit in with the other sums around it. When introducing the Kakuro, you’ll need to include in your layout the explanation and table of Unique Blocks (which you may copy and use from the How to tab on each Kakuro puzzle view).