Question

How Will the number of ordinary years & leap years in a century be calculated ? Please explain in details. Thank you.

Answer 1

In the Gregorian calendar 3 criteria must be taken into account to identify leap years:

• The year is evenly divisible by 4;
• If the year can be evenly divided by 100, it is NOT a leap year, unless;
• The year is also evenly divisible by 400. Then it is a leap year.

So by these rules, the years 400, 404, 408, 800, 896, 1200, 1600, 2000, 2004 and so on are leap years, while 500, 600, 700.. 1100, 2100 aren't leap years as they aren't divisible by 400 ( though divisible by 4 and 100)

Between 1795 and 1805 the leap years were 1796 and 1804. 1800 wasn't a leap year. And between 1995 and 2005 the leap years were 1996, 2000 and 2004.

So by this logic NOT ALL 100 years have 24 leap years and 76 non-leap years.
For example: years 1801 - 1900 had 24 leap years:
1804, 1808, 1812, 1816, 1820, 1824, 1828, 1832, 1836, 1840, 1844, 1848, 1852, 1856, 1860, 1864, 1868, 1872, 1876, 1880, 1884, 1888, 1892, 1896.

While years 1901 - 2000 had 25 leap years and 75 non-leap years:
1904, 1908, 1912, 1916, 1920, 1924, 1928, 1932, 1936, 1940, 1944, 1948, 1952, 1956, 1960, 1964, 1968, 1972, 1976, 1980, 1984, 1988, 1992, 1996, 2000.