wethere 2000 and 2100 are leap years .any one of that leap year and other is not, why?

Answer 1

For years ending in 00, you need to survive three questions:

1. Is the year number divisible by 4?
If no, then it is not a leap year. If yes, go to question 2:

2. Are the last two digits 00?
If no, then it is a leap year.
If yes, then go to question 3.

3. Is the date divisible by 400?
If no, not a leap year.
If yes, it is a leap year.

2008:
1. yes (divisible by 4)
2. no (does not end with 00) therefore it is a leap year.

2000:
1. yes (divisible by 4)
2. yes (ends with 00)
3. yes (divisible by 400) therefore it is a leap year.

2100
1. yes (divisible by 4)
2. yes (ends with 00)
3. no (not divible by 400), not a leap year.

2007
1. no (not divisible by 4), not a leap year.

2400 will be a leap year.
3000 will NOT be a leap year (unless the rule changes before then).


When only question 1 was in effect, the calendar year was exactly 365.25 days on average, which is a tiny bit longer than the real (tropical) year of 365.24219 days.

With the addition of questions 2 and 3, in the 16th century (and the removal of 10 days), this made the calendar year come out to an average of 365.2425 days (called the "Gregorian year" because the change was made by pope Gregory XIII in 1582).

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Nothing to do with the question, but:

It is this gregorian year that is used when determining the length of a "light-year".

365.2425 days * 86,400 seconds/day * 299,792,458 metres/second
(multiply all three numbers to find the length of a light-year in metres)

Answer 2

2000 was a leap year, but 2100 will NOT be a leap year.

Before 1582, all years divisible by 4 were leap years. That was the "Julian Calendar."

After 1582, the rule changed to :
1) all years divisible by 400 are leap years;
2) years divisible by 100 are NOT leap years, except for rule 1.
3) years divisible by 4 are leap years, except for rule 2.

This is known as the "Gregorian Calendar."

Answer 3

The old rule was that years divisible by 4 were leap years, unless they were also divisible by 100, when they were not; however, there was a further exception: years divisible by 1000 are leap years. Ergo,
The year 2000 was a leap year.
The year 2100 will not be a leap year.
Whether there will be a consensus about this in 2100 is another question.

Answer 4

2000 was a leap year, but 2100 will notbe . The rule is that if the year is divisible by 4 it is a leap year but if it is divisible by 100, then it is a leap year only if it is divisible by 400.

Answer 5

2000 was not a leap year, 2100 will be a leap year because 2000 is evenly divided by 400 and 2100 is not.