A leap year occurs every four years, right? Well, unfortunately it is a little more complicated than that. Because the Earth’s revolution around the sun is just slightly less than 365.25 days, every once in a while a leap year must be skipped to keep our seasons on track.
Most of us were taught if a year is divisible by 4, it is a leap year. However, there is an exception to every rule. In the case of leap years, the exception happens in century years, or years ending with two zeros. A century year is not a leap year unless it is also divisible by 400. This means that 2000 was a leap year, but 1900 was not, and 2100 will be skipped as well.