Figuring DOB From Tombstones

Here is how to figure the date of birth from a death date and age on a tombstone if you don't have a computer handy to do the calculation for you:

Remember 8870

That's not an error: It's the number to remember when you want to find the birthdate of someone when you only have the date of death and age. How do you figure the birthdate?

Suppose the person died May 6, 1889, at the age of 71 years, 7 months, 9 days.

That result can be interpreted as: Year 1817, 9th month (Sept), 27th day or 27 Sept, 1817

From Platte Co, MO Historical/Genealogical Society