I have it in an adobe PDF file.  The formula is in the Properties section.   

I really apricate your response. I don't know how to do what your asking.   I am very new to calculations in adobe so if there is something very basic I canfollow I can apply it and hopefully learn from it. 

I am trying to calculate the percent difference between two numbers whether it is greater than the original number or less than the original number.      My Original Number is "A1" and by new number is "A2".   The formula I am using is : event.value = Math.abs(Number(this.getField("A1").valueAsStrin...