So here I am slaving away, hard at work.. /cough

I'm putting together a database to track things in my office and one of them is graphics work. The idea being that we charge so much per scan, up to a certain file size. IE if it's huge it takes the Graphics guys more time than average. So, using filemaker pro 8, I have the current equation set and it works great, but it spits out negative numbers which is not so great. Anybody know a way to make it either return a zero if the answer is negative, or to exclude the answer when totaling the cost if it is negative?

As it stands now my equation is: File Size in MB - (No. Scans *30) * 1.00

The idea being each scan gets a 30MB limit, but if you have like 6 5mb files and 1 50mb file you wont pay the overage.

Though using that example with my calculation currently will yield a negative number. i.e. 80 - (6*30) * 1.00 = -100.00

I've tried using the range validation, which works once, but if you go back and change the numbers it borks it =\

Another option would be if there is some way of exluding that negative number when adding up the grand total.

Lehp muh!

Edit: Found a way to script it in, but if anybody knows how to make it part of the equation I'd appreciate it.