Originally Written by: Trevor Harris, Physics Dept., University of Adelaide,
20/09/88
November 2004: correction for century years... S. Masson;
Every year divisible by 4 is a leap year.
But every year divisible by 100 is NOT a leap year
Unless the year is also divisible by 400, then it is still a
leap year.
This means that year 1800, 1900, 2100, 2200, 2300 and 2500 are
NOT leap years, while year 2000 and 2400 are leap years.
+ supress the automatic change 89 -> 1989
June 2005 update for new commons, Sebastien Masson.