Pro-rata calculation

Hi,
I have two fields in a membership application form.

• One is a List "[join_membership_type]" to select the type of membership required (e.g. Adult, Junior, Family) and it is set on a monthly $ rate. For example, the family monthly rate is $75, adult monthly rate $37.50 and junior monthly rate $12.50.
• The other is a List "[join_month]" to select the current month, from March through to February, with associated values decreasing from 12 down to 1. The purpose is to calculate a pro-rata fee to the end of the membership year . For example, someone joining in September will pay the monthly fee * 6, someone joining in December will pay the monthly fee * 3.

I want the total amount of my form to include [join_membership_type] * [join_month] (plus a couple of other fixed fields).
How would I set this up?

Of course, it would be even better if the calculation could just be done by the system month!

Also, can you have 'hidden' fields, that calculate from other fields but don't show?

Hi

Maybe send me super admin account of your site and the link to the form so that I can try setup it for you? It is a bit complicated, so it is difficult me to explain than actual setup it.

So maybe I can setup it for you as a sample so that you can understand how it works and can setup other forms yourself ?

Of course, it would be even better if the calculation could just be done by the system month!

=> Not possible

Also, can you have 'hidden' fields, that calculate from other fields but don't show?

=> Not possible