[kqr]

Also in case you did not know, the leap year is not on even hundreds of years, i.e. 1900 was not a leap year, and neither will 2100 be under the current calendar.

The exception is every four hundred years, which means 2000 was a leap year, as would 1600 have been, and 2400 will be.

This means the year is on average 365.2425 days long[1] -- a constant that I've found surprisingly useful to memorise.

[1]: Because 365 + 1/4 - 1/100 + 1/400.

[beardyw]

> as would 1600 have been

Though the Gregorian calendar wasn't adopted in England and America * until 1752, so no 100s or 1000s under the old calendar.

* And probably a lot of other places