If you think you have trouble remembering important dates, such as birthdays and anniversaries, just think about how George Washington must have felt.
Today, February 22nd, as any school kid could tell you, is Washington's Birthday, but technically he wasn't born on this date.
According to historical accounts (I wasn't there) George Washington was born on February 11, 1731 under the Julian calendar. That same year New Year's Day was celebrated in March. Then with the adoption of the Gregorian calendar in 1752, February 11, 1731 became February 22, 1732.
By the way, did you know that 1732 - the commonly accepted birth year of George Washington - is essentially the square root of 3 (1.732)?
Anyway, as if that wasn't enough confusion, Washington's Birthday became the 3rd Monday in February in 1971. Even though it's known as Presidents' Day (seen with and without the apostrophe and shown as both singular and plural possessive) and honors all of the country's 43 Presidents, the day really is meant to commemorate George Washington's Birthday because that was the only official federal holiday (on February 22nd) prior to 1971.