My form has several fields for numeric values to be entered. At the bottom is a total field. 

I set an "on user input" script for each field as follows to update my overall total at the bottom:

input.Total = (input.Total  +  input.FIELD1Value); field 2 value etc..

This works fine and when I tab out of field the total updates.

BUT..

If I go back to FIELD1 and change the value it adds this new value to the total also, so my total is way off as it has not reduced the initial value.

Can someone help me to ensure my totals are correct for the actual values on screen? Can I reset or recalculate the total when any filed is updated?

Help would be appreciated.

Rob