How many integers between 1 and 200, including both 1 and 200, are divisible by 4 or 5?

Answer 1

For integers between 1 and 200:

    Divisible by 4:    50

    Divisible by 5:    40

    Divisible by both 4 and 5 [that is, divisible by 20]:  10    [count only once]

Divisible by 4 or 5:  50 + 40 - 10 = 80