Consider the following years : 1600, 1700, 1800, 1900, 2000, 2100, 2200, 2300 and 2400 How many leap years are there in the above?

According to the Gregorian calendar rules, a year is a leap year if it is divisible by 4, but century years (those divisible by 100) are only leap years if they are also divisible by 400 [3]. This rule was established to correct the slight inaccuracy of the Julian calendar and better synchronize with the Earth's revolution [2]. Applying this rule to the given list: 1600, 2000, and 2400 are divisible by 400 and are therefore leap years. However, the years 1700, 1800, 1900, 2100, 2200, and 2300 are divisible by 100 but not by 400, so they are not leap years [1]. Consequently, there are exactly 3 leap years (1600, 2000, and 2400) in the provided list.

Sources

1. [1] Exploring Society:India and Beyond. Social Science-Class VI . NCERT(Revised ed 2025) > Chapter 4: Timeline and Sources of History > How Is Time Measured in History? > p. 62
2. [3] https://www.bbc.com/future/article/20240228-leap-year-the-imperfect-solution-to-fix-the-calendar
3. [2] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 11: Keeping Time with the Skies > A step further > p. 180