You can try the formula below by Shirley Scott or you can go to Obituary Central's Birthday Calculator to figure out the date.
by Shirley A. Scott
The tombstone says they died at 71y, 7m, 9d on May 6, 1889. Follow these
simple instructions for an accurate way to find their date of birth.
Using a calculator, enter date of death in numbers by year, month and then
day. 1889 May 6 would be entered as 18890506.
Subtract the age of person found on a tombstone. 71 y, 7 m, 9 d would be
entered as 710709. Subtract that from 18890506. You will get an answer of
18179797.
Subtract 8870 from 18179797 to correct the months and days. The answer will
be 18170927.
Translate 18170927 back into year, month and day. You will have 1817
September 27 as the date of birth.
If you have access to any Birth Record index that you would be willing to share, please let me know. We can always ask for volunteers to help type it!
Indiana did not require Birth or Death Certifications until 1882.