## Leap-Year Rules

Since 1582 (1752 in USA and other years in other countries), the following is the currently
widely-unknown leap-year rule:

A year is a leap-year if it is evenly divisible by 4 **unless** it is evenly divisible by 100, **UNLESS**
it is evenly divisible by 400. This means that 1800, 1900, and 2100 are NOT leap years, but 2000 IS a leap year,
since it is evenly divisible by 400!