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Suppose you find an ancestor's headstone relating that he died 6 May 1889 at the age of 71 years, 7 months and 9 days. Quick, what was his birth date? You can eventually figure it out by using your fingers, toes and calendar, but there is a quicker and easier way.

I found the following interesting and useful material from the Platte Co, MO Historical/Genealogical.

Remember 8870. It's the number to remember when you want to find the birthdate of someone when you only have the person's date of death and age. Here is how to do it: (You may have to change your browser font size to line your numbers up right.)

• Write the date of death as year-month-day: 18890506
• Write the age as years-months-days: . . . . . . . .710709
• Subtract the bottom number to give. . . . . . . 18179797
• Subtract 8870. . . . . . . . . . . . . . . . . . . . . . . . . . . . . -8870
• Leaving a total of . . . . . . . . . . . . . . . . . . . . . . . 18170927 = 1817-09-27
• So, his birth date was in 1817, 9th month and 27th day = 27 Sep 1817.

If you have any information about the ancestors or descendants of any of the folks mentioned in this article, please contact us at dewald@prenticenet.com.