February 29 is a date that usually occurs every four years, and is called the leap day. This day is added to the calendar in leap years as a corrective measure, because the earth does not orbit the sun in precisely 365 days.

While an ordinary year has 365 days, a leap year has 366 days. Occurrence of the leap year after every four years, makes the leap year divisible by 4.

**Formula to calculate leap year.**

- We begin by identifying the year we want to know if its a leap year.
- We then divide the year by 4 to check if its evenly divisible.
- Then confirm that the year is not evenly divisible by 100.
- Check if the year is divisible by 400.

If the year is not evenly divisible by 100 and 400, then it is not a leap year. If the year is only evenly divisible by 100 and not evenly divisible by 400, then the year is not a leap year. If the year is evenly divisible by both 100 and 400, then the year is a leap year.

**Example:**

Determine whether 2020 is a leap year.

Therefore, the year 2020 is not a leap year.