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Leap years are those with 366 days (Gregorian calendar) and consist of 13 months (lunar calendar). In English, leap years can be referred to as 'leap year' or 'intercalary year'. The purpose of having leap years is to add days and months to the calendar year to synchronize it with the seasonal year.
The Gregorian calendar year is based on the Earth's orbit around the Sun, with a period of 365 days, 5 hours, 48 minutes, and 46 seconds for one revolution. Therefore, the Gregorian calendar year is rounded to 365 days. The remainder accumulates, and every 4 years, 1 day is added. This extra day is added to February, making it 29 days. Thus, in leap years, February has 29 days instead of the usual 28 days in a common year.
As for the lunar calendar, it follows the cycles of the Moon. A lunar month consists of 29.53 days, so a lunar year is rounded to 354 days. The surplus time after 3 years can accumulate into an extra month (33 days). Hence, lunar years have an additional '13th month' to synchronize with the seasonal cycle.
The most accurate method of calculating leap years
Calculating leap years in the Gregorian calendar
As explained above, in the Gregorian calendar, every 4 years an extra day is added. Therefore, to determine whether a year is a leap year or not, the following method is applied:
Method 1: Take the given Gregorian year and divide it by 4. If there is no remainder, then it is a leap year.
For example:
+) The year 2020 is a leap year because 2020/4 = 505 with no remainder
+) The year 2013 is not a leap year because 2013/4 = 503 with a remainder of 1
Method 2: For years ending in 00, they must be divisible by 400 instead of 4 to be a leap year, if there's no remainder, it's a leap year.
For example:
+) Year 1600/400 = 4 => leap year
+) Year 1700/400 = 4 with a remainder of 1 => not a leap year
Calculating leap years in the lunar calendar
In the lunar calendar, a leap year will have an additional month, making a total of 13 months in the year. Each lunar year consists of 354 days, deviating approximately 11 days from the Gregorian calendar. Adding an extra month to the lunar calendar helps to bring the total number of days closer to 365 days. However, to maintain synchronization with the phases of the Moon, 7 leap months will occur in 19 years. Therefore, the specific method for calculating leap years is as follows:
Divide the lunar years by 19, if the remainder is any of the following numbers: 0, 3, 6, 9, 11, 14, 17, then it is a leap year.
For example:
+) The lunar year 2020 is a leap year because 2020 divided by 19 leaves a remainder of 6
+) The lunar year 2019 is not a leap year because when divided by 19, there is a remainder of 5
The information provided by Mytour above has helped readers understand What is a leap year? The most accurate method of calculating leap years, so that you do not confuse lunar and Gregorian years with each other. Besides learning about leap years, many people are still unclear about how many days are in a year, a week, a quarter to be able to organize, plan their work and their intentions.
