Question

I have the following exercise but am not sure on how I should begin. The wording doesn’t make sense to me:

Using the addition function over the
natural numbers, give a recursive
definition of multiplication of
natural numbers.

Answer 1

You can think of 3 * 5 as 5 + 5 + 5, i.e. adding 5 for 3 times. If you want to do it recursively, then you can think of it like this: the result of a * b is equal to adding b to the result of (a-1) * b. From here to a Haskell recursive function, the step is small 🙂