Moodle - Calculated Questions

Hi - just found this forum and I think its going to be a great help to me: Thanks in advance!

I'm a maths teacher and at the start of the term I set up our school's VLE using Moodle and the more I play with it, the more I like it!

Anyway, here's my question:

I've found out how to use (say) {a} to generate a random number in a calculated question, but can I combine several random numbers to create another number in the question?

For example, lets say a want to make a division question where the answer will always be an integer. To do this, I would take two numbers, say a and b, multiply them together and the question becomes axb divided by a, giving the answer b.

This is how I tried to set up a Moodle Calculated question:

{a}*{b} divided by {a} [lets say a=3 b = 4]

but it displays as;

3*4 divided by 3

not:

12 divided by 3 (which is what I want it to say)

Any help gratefully received!

Jeff