Every four years, an extra day is added to the calendar, But even with leap day, the math doesn't exactly, well, math.

Feb. 29 is more than just an extra day we have once every four years. There is some science behind it. Here's how leap days ...

The Western world celebrates New Year's ... his Julian calendar, as it came to be known, was the first to codify it as such and ensured that Jan. 1 and other significant dates would never again ...

4 Leap years were introduced by the Roman emperor Julius Caesar, who created a new calendar to take the extra quarter-days into account. The Julian calendar ... the exact date on which this ...

He introduced his Julian calendar in 46 BCE. It was purely solar and counted a year at ... t have that date built in. There are about 5 million people worldwide who share the leap birthday out ...

Prior to the Gregorian and even Julian calendars ... emperor adopted a 365-day calendar and added 10 days the calendar, including a leap day in February every four years, calendar.com said.