> However, there is still a small error that must be accounted for. To eliminate this error, the Gregorian calendar stipulates that a year that is evenly divisible by 100 (for example, 1900) is a leap year only if it is also evenly divisible by 400.

> For this reason, the following years are not leap years:

> 1700, 1800, 1900, 2100, 2200, 2300, 2500, 2600

I had no idea!