Western History & Genealogy Blog


Tombstone Math

Here's a shortcut for calculating a birth date when the death date is given on the tombstone or in an obituary, but only the age in years, months and days.

It is called the 8870 formula.

Here's how to use the "magic" 8870 formula.

Here's an example: Ancestor died May 6, 1889 at the age of 71 years, 7 months and 9 days, convert those to numbers