Leap years, 29th February

February was the Moon is unique among the other month. Anyone knows? Yup, the 29th. Been years in the previous month only two stops on the 28th? But this was different, because of the establishment named in Leap.

Leap years are years in which the number of days that there is increased by one to 366 days. Starting from a few thousand years ago in the days of Julius's Caesar led the Roman Empire. At that time, the calendar that is very confusing and misses of the calculation. Therefore, an expert on astrology called Sosigenes asked to make a fixed calendar.

When fixing the date, Sosigenes said that within one year of the earth takes 365.25 days. But for ease, Sosigenes engage to 365 days. Where the rest? Sosigenes merge them into one day every four years. Well, that's called a leap year. Month of February was also chosen as the month is added for the least number of days each year.

In addition to the increase today, there is another uniqueness of Leap year. Apparently, if we count, the numbers will the leap year is divisible by four. Well cool! However, many are confused, what if someone was born in the year on February 29 leap year?

Because, basically, a leap year is the year of rounding, so the calculation of the date of someone's birthday on December 29 only gets a small once in four years.

Description from Wikipedia

Leap Year is a Syamsiah year in which the number of days in that year is made ​​up of 365 days but 366 days.

One year Syamsiah not exactly made ​​up of 365 days, but 365 days 5 hours 48 minutes 45.1814 seconds. If this is ignored, then every 4 years to be deprived of almost 1 day (exactly 23 hours 15 minutes 0.7256 seconds.

So to compensate for this, every four years (years that can be divided by 4), was given an extra day: February 29. But since 5 hours 48 minutes 45.1814 seconds less than 6 hours, then the years can be divided by 100 (as of 1900), are not leap years unless divisible by 400 (as of 2000).

Algorithms.

There is a simple algorithm to determine whether a year, including leap year or not as follows:

If the year number is divisible by 400, the year it is definitely a leap year.

If the year number is divisible by 400 but not divisible by 100, the year it is certainly not a leap year.

If the year number is not divisible by 400, not divisible by 100, but it is divisible by 4, then the year is a leap year.

If the number of years not divisible by 400, not divisible by 100, and not divisible by 4, then the year is not a leap year.

Leap year according to this definition there since the launch of the Gregorian calendar (1582).