Excel can't do this on its own, but this would help:
http://www.j-walk.com/ss/excel/usertips/tip028.htm


tj

"David Cleave" wrote:

Hi all

How do I get Excel to deal with dates before 1900? How about if I wanted to
use Excel to calculate length of William Is reign (from 25/12/1066 to
09/09/1087)?

Thanks

David