Option multiplier

I was wondering if it was possible to get an option to multiply the price rather than add to it.

Say I want to sell some carpet, base price is 1 cent per square inch. Every inch in length adds 1 cent, but the width selector should multiply the price for every inch. I know theres an addon out there already for 35 bucks, but it would be nice to put something as simple as a multiplier (+ and - are already in there it seems) in the core files.

Hi, how about pricing based on area of the carpet.... Hope I understood the question..

Which extension you are using... ?

Thanks & regards,