How do you experts implement form calculations? What I mean by this is, a form has several numeric fields and I want to make calculations based on these fields and display the results on the form, updating the results every time there is a change.

When the form is displayed, it should calculate and display the results. When there are any changes in the numeric fields it should recalculate and display the results.

In that I am not much of a programmer, the more specific the answer the better.

Thanks.