Condition for leap year.
1) The year is evenly divisible by 4.
2) If the year can be evenly divided by 100 ,then it is not leap year unless the year is also evenly divisible by 400,then it is leap year.
For 2016, it is not divisible by 100 so if satisfies (1) then its a leap year,ie 2016/4=504 ,
This means that 2000 and 2400 are leap years, while 1800, 1900, 2100, 2200, 2300 and 2500 are NOT leap years.