Been looking around the internet and cannot seem to word my question good enough to produce anything close to what I want to do. I wrote a form for use at a golf course I work at. It is a form for keeping pesticide records. I am trying to figure out how to get in to mutiply 2 text input boxes together and autofill other ones with the result.

I have to input ounces of chemical used per 1000 ft²
I have to input acres sprayed

I would like to have the form autofill sections for Amount of chemical used per acre and total amount of chemical used. I know all the math involved I just can't figure out how to make it do it in html. I can post my code if needed.