How to create a calculated field in MS Word 2

[Badkitty]

I am trying to create a calculated field in MS Word. What I want is for the field to automatically update a number in a sentence like:
The company has been in business for XX-years.
I know the company was founded in 1946, so where do I go to subtract 1946 from the current date? I want this to automatically stay updated so that each time (or year) a user opens the document, it will reflect the correct difference between the two years.
Thanks!

 

[carrr]

http://cps.uwsp.edu/support/PC/Word97/Forms-Calculation.htm

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