but my ques is that y year hving 00 in the last should be divisible by 400 .

eg 1900 is divisible by 4 but it is not divisible by 400 so it is not considered as a leap year. y?

In general, an year is considered as a leap year if it is divisible by 4 not by 100.

For example, 1992, 1996, 2004 etc.

Now, if a year is divisible by both 4 and 100 then it must be divisible by 400 in order to be a leap year.

For example, year 1900 is divisible by both 4 and 100 but it isn't completely divisible by 400. Hence, 1900 isn't a leap year.

Again consider the year 2000, it is divisible by both 4 and 100. Now, we check whether it is divisible by 400 or not.

 which is completely divisible by 400.

Therefore, year 2000 is a leap year.