I need to calculate the difference between two dates, one of which could be
before 1900. The YEAR function doesn't seem to work on dates earlier than
1900.
What's the best and most efficient way to detect a date is before 1900,
extract the year and use that number in a subtraction?
More specifically, I'm interested in calculating the age of several passed
away VIPs of human mankind.

Thanks, Stefano