Question

How many integers from 1 to 40 inclusive are multiples of 4 or 5?

Answer 1

Multiples of 4 =10

Multiples of 5 =8

Answer 2

Multiplies of 4 :

4, 8, 12, 16, 20, 24, 28, 32, 36, 40

⇒ There are 10 integers that are multiples of 4

Multiples of 5:

5, 10, 15, 20, 25, 30, 35, 40

⇒ There are 8 integers that are multiples of 5

Multiples of both 4 and 5:

20, 40

⇒ There are 2 integers that are multiples of both 4 and 5

Find the number of integers:

Total number of integers that are multiples of 4 and 5 = 10 + 8 - 2 = 16

Answer: 16