How to calculate leap year

A leap year is a year that is divisible by 4 but not divisible by 100, except when the year is divisible by 400.

Step-by-Step Explanation

Divisible by 4:

Most years that are divisible by 4 are leap years. For example, 2024 is divisible by 4, so it’s likely a leap year.

Not Divisible by 100:

If the year is also divisible by 100, it is not a leap year. For instance, 1900 is divisible by 100, so it’s not a leap year.

Divisible by 400:

If the year is divisible by both 100 and 400, it is a leap year. For example, 1600 and 2000 are divisible by 400, so they are leap years.

Rules Summarized

• If the year is divisible by 4, go to step 2.
• If the year is not divisible by 4, it is a common year (not a leap year).
• If the year is divisible by 100, go to step 3.
• If the year is not divisible by 100, it is a leap year.
• If the year is divisible by 400, it is a leap year.
• If the year is not divisible by 400, it is a common year.

Examples

Year 2020:

• 2020 ÷ 4 = 505 → Divisible by 4
• 2020 ÷ 100 = 20.2 → Not divisible by 100
• Therefore, 2020 is a leap year.

Year 1900:

• 1900 ÷ 4 = 475 → Divisible by 4
• 1900 ÷ 100 = 19 → Divisible by 100
• 1900 ÷ 400 = 4.75 → Not divisible by 400
• Therefore, 1900 is not a leap year.

Year 2000:

• 2000 ÷ 4 = 500 → Divisible by 4
• 2000 ÷ 100 = 20 → Divisible by 100
• 2000 ÷ 400 = 5 → Divisible by 400
• Therefore, 2000 is a leap year.