Calculation to sort fields by the values of two others

[michaelbriordan]

I am compiling a library of books which have a "series" number, and a "volume" number.

So for instance:

Book Title, Series, Vol in series

My book, 1, 3

His book, 2, 4

Her book, 3, 7

I want to sort this by a book's position within the whole series, so I need a calculation field to do this for me, which I can then ask FM to sort.

What is the calculation I need to do this?

[comment]

Why not simply sort by both fields?