debunking an email myth

My dad just sent this email below to me, stating that this August with five Sundays, Mondays, and Tuesdays only happens only once every 823 years.

I got thinking for a few seconds, and realized it wasn’t true. So I hit “reply all” to debunk the myth, telling my dad to return the email himself!

My reply:

I hope I am around the next time August has five Sundays, Mondays, and Tuesdays. It will be in the year 2021! And if I’m not mistaken, it happened in 1998 and 1992. It will also happen in 2027 and 2034. And that’s just August! It happens every time a 31-day month starts on Sunday.

From: Bill Murphy
Sent: Wednesday, August 25, 2010 1:25 PM
Subject: AUGUST 2010

AN INTERESTING FACT ABOUT AUGUST 2010.

This August has 5 Sundays, 5 Mondays, 5 Tuesdays, all in one month.
It happens once in 823 years.

I wanted to let you know now because I'll probably miss it next time!