How many leap years from 1980 to 1990?

I first answered this question in August 2010. It is now January 2018, so I'll update it:

Not sure if you're wanting 1980 included or not since it was a leap year.

Leap years are those years which are divisible by 4 EXCEPT for centuries when the century must be divisible by 400; they occur every four years (except possible when a century ends).

2000 IS divisible by 400 so it was a leap year.

As 1980 was a leap year, by subtracting 1980 from the current year, dividing by 4 and ignoring any remainder, the number of leap years after 1980 is found.

(2018 - 1980) ÷ 4 = 38 ÷ 4 = 9 r 2 → 9 leap years after 1980

Including 1980 there have been 10 leap years: 1980, 1984, 1988, 1992, 1996, 2000, 2004, 2008, 2012, 2016

Excluding 1980, the first leap year after 1980 was 1984 there have been 9.

The next leap years will be 2020, 2024, 2028, 2032, ...

These are the years of the Summer Olympic games.