If the document used formfields for the inputs, setting their 'calculate on exit' property and applying forms protection would result in automatic calculations. Do note, though, that calculation formfields are known to produce spurious results when getting inputs from other calculation formfields. You can avoid that by using formula fields for all the calculations. Alternatively, you could stick with your current setup and, instead of having to update the fields individually, use Ctrl-A, F9 to update all fields simultaneously.
To see how to a wide range of calculations in Word, check out my
Microsoft Word Field Maths Tutorial, at:
http://windowssecrets.com/forums/sho...Maths-Tutorial
or:
http://www.gmayor.com/downloads.htm#Third_party