Leap years algorithm. Examples of leap years.

Leap years algorithm.

Every year that is evenly divisible by 4 is a leap year, except for years that are evenly divisible by 100, but these years are leap years if they are evenly divisible by 400:

  • 1) A leap year can be evenly divided by 4.
  • 2) Except if it can be evenly divided by 100 then it isn't a leap year.
  • 3) Except if it can be evenly divided by 400, then it's a leap year.

How often do the leap years occur in the calendar?

Nearly once every four years, more exactly, 97 leap years at every 400 years.

Nearly once every four years is a leap year, and these years must be multiples of 4. More precisely, as we can calculate above, leap years happen in a cycle of 97 years out of every 400.


Examples of leap years.

  • Examples of leap years which are multiples of 4 but not of 100 nor of 400: 1584, 1588, 1596, 1956, 1960, 1964, 1968, 1972, 1976, 1980, 1984, 1988, 1992, 1996, 2004, 2008, 2012, 2016, 2020, 2024, 2028, etc.
  • Examples of common years (NOT LEAP YEARS), which are multiples of 100, but not of 400: 1700, 1800, 1900, 2100, 2200, 2300 - these are not leap years.
  • Example of leap years which are multiples of 400: 1600, 2000, 2400.