Why was 2012 a leap year?

Answer 1

The time it takes Earth to orbit the sun once is about 365.24219 days. Since that is not a whole number, in order to keep the seasons starting at the same times each year 24.219% of all years would have to have 366 days each while the other 75.781% has 365 days each. The way that was implemented was to make 97 out of every 400 years leap years by adding the 29th of February. A year is a leap year if it is evenly divisible by 4, like 2012 and 2016, unless it is also evenly divisible by 100, like 1900 and 2100. Then it is not a leap year, unless it is also evenly divisible by 400, like 2000 and 2400. Then it is a leap year. That system makes the average number of days per calendar year 365.2425.

Answer 2

2020 is a leap year because it is divisible by 4, with no remainder. Years that are both divisible by 100 and not divisible by 400 are leap years too, but that rule does not apply to 2020.