How to figure date of birth from gravestone inscriptions

Often times, gravestones mention the deceased person with only their age in years, months and days, making it difficult to accurately come up with their actual date of birth. Below is a formula commonly used to help with this problem.

What You Do Know: James Hooligan died May 16th, 1847 and was 57 years, 6 months and 18 days of age.

1.        Make the date of death into a number format (year, month, day): 

1847, May 12th. = 1847 05 12.

Note: make sure to place a 0 in front of all months Jan to Sept. Jan = 01, Feb.=02 etc.

Same with calendar days 1-9, 1st=01, 2nd=02 etc

2.        Now calculate the available age information into a number format:

57 years, 6 mo, 18 days = 57 06 18.

3.        Using your dates converted to the numerical format subtract the persons age from the date of death,

                                          18470516

                                           - 570618

                                          17899898

4.        Now subtract 8870 from your total            (I don’t know why it works, but it does!)

                                           17899898

                                               -   8870

                                           17891028   

(1789-year, 10th-month, 28th-day) James was born Oct. 28th, 1789 !!!

If your month column is more than 12, subtract 12 and add 1 more year to your answer. If the day column is more than 30, subtract 30 from the day column and add 1 more month.