Which of the following is not a leap year?

Explanation:

Rule: A year is a leap year if it is divisible by 4. However, years divisible by 100 are not leap years unless they are also divisible by 400.

• 1600 — divisible by 400 (1600 ÷ 400 = 4), so it is a leap year.

• 1200 — divisible by 400 (1200 ÷ 400 = 3), so it is a leap year.

• 800 — divisible by 400 (800 ÷ 400 = 2), so it is a leap year.

• 500 — divisible by 100 but not by 400 (500 ÷ 400 = 1.25), so it is not a leap year.

Therefore, 500 is not a leap year.