Using dates preceding 1900 in excel

[J-Griff]

Hello,

I am trying to incorporate the below into my existing spreadsheet in order to correctly format dates preceding the year 1900. However, I am an excel novice and cannot seem to figure it out? I have attached my original spreadsheet titled Family Newspaper Articles and the Earlydates spreadsheet workaround. 

Any help is greatly appreciated. 

Sincerely,

John 

[#2 · Accepted solution]

@J-Griff 

I thought that the cycle repeats every 100 years but trying the pattern didn't seem to be quite consistent.  What appears to work is that adding 2000 years is the same as adding 730485 days.

So to get a datevalue (negative) for a date dd/mm/yyyy in the 1700s (say) add 2000 to the year and use 

= DATE( 2000+yyyy, mm, dd ) - 730485

Going the other way adding 730485 to a negative serial date will show the correct day and month but 2000 years forward.