How did my timex ironman watch know this was a leap year?

Question

The watch doesn't have the year in it's memory, and there doesn't seem to be any pattern to leap years, so how did my watch know to go to Feb. 29 today?

Answer 1

I guess it keeps track of not just the date, but also the day, month, and the year so that the watch knows how many days are in the current month, and even takes leap years into account.

Answer 2

It is in it's memory to know the month, day, and year, just like your computer, but on a smalle scale/