How to calculate quantity from drop downs and text fields

Hi There!

I have a general understanding of Acrobat, but have not used the form tools very much.

In a nutshell, I am creating an order form where the customer chooses their item from a drop down and in the next field they enter the quantity. I am wanting to have a totaling feature added to the bottom of the form to calculate the total quantity ordered for each item in the drop down list.

Is this possible?

Thanks in advance!