If you can divide last two digits of the year completely with 4, it would be a leap year
Eg. xx40, xx24, xx96 etc are leap years and
xx39, xx41, xx42 are not.
In the case of centuries, if you can divide the year with 400, it would be a leap year.
Eg. 1600, 2000 etc are leap years and
1500, 1900, 2100 are not.