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Feb20

# Math Can Explain Why 2020 Is a Leap Year

At Smartick we know that math is behind almost everything, and a leap year is no different. The reasons related to the Julian calendar and subsequent change of the Gregorian calendar are well known. However, the mathematical reasons that determine whether or not a year is a leap year are lesser-known.

So, in order to know if a year will have 365 or 366 days you need to activate the arithmetic skills and prepare to do the math. This year has 366 days and mathematics can explain why 2020 is a leap year.

#### How do we know if a year is a leap year?

• All leap years are divisible by 4.
• The years that are divisible by 4, but not by 100, are leap years.
• The years that are divisible by 100, but not by 400, are not leap years.
• However, the years divisible by 100 and 400 are leap years.

With these simple division problems, we can know, with certainty, when we will enjoy 29 days in the month of February.

Roman Emperor Julius Caesar is credited with creating the leap year because he proposed the idea to recover the time lost during a ”normal” year. According to the movement of the Earth around the Sun, a year is actually 365 days, 5 hours, 48 minutes and 56 seconds. Therefore, Caesar proposed that an extra day should be added to the calendar every four years, the famous 29th of February. But by using this method, there was still a discrepancy. Pope Gregory XIII suggested the aforementioned exceptions in order to correct the gap in the Julian calendar. Thus, every 400 years there are three years that are not leap years.

The month of February previously had 30 days and was chosen to have the extra day. The extra day is known as bissextus. Although the word is not widely used, it comes from the Latin word which referred to February 24, six days before the Calends of March. The emperors Julius Caesar and Caesar Augustus wanted their months (July and August) to have 31 days each. As a result, days were removed from February and added to their months. This left the second month of the year (previously 30 days; 31 in leap years) with 28 days and 29 during leap years.

Our students at Smartick are used to completing math exercises – presented in real-life situations like this one – and are trained in problem-solving and logical thinking. They should have no problem calculating if, for example, the year 2530 will be a leap year or not. What do you think? Leave us your answer in the comments.