I have just been playing about with dates & datevalues
(in connection with dacius1's thread)
and decided to see what date Serial_Number 0 represents.

I got back the answer 0/1/1900! (note UK data format)
Thus date Serial_Number 1 represents 1st of January 1900.
Any date earlier than this appears to be beyond the ability of Excel.

Does this mean that if I were an antiquarian or genealogist who regularly deals with dates over 107 years ago, Excel would not be able to calculate (for example) the age of my great-grandfather at death given his birth and death dates?

Perhaps I'm just being picky, and it will probably never be a problem I will encounter, but...

Mark.