Question

The least common multiple of 20, 24, and 45 is _____.

a) 30
b) 180
c) 360
d) 21,600

Answer 1

c) 360
because they can all be multiplied to get 360
20 times 18 24 times 15 45 times 8

Answer 2

c)360

Explanation:

The least common multiples is the smallest common multiple.

To find the common multiple you have to divide the option given by the numbers: 20, 24, and 45 and result of each operation should be an integer number.

Let's review why answers a) and b) are not common multiple.

Answer a) 30

45 ÷ 30= 1,5 .

1.5 is not integer number ,So, 30 is not multiple of 45.

Answer b)180

180 ÷ 24= 7.5

7.5 is not integer number, So, 180 is not multiple of 24.

c) If you divide 20, 24 and 45 divided 360, the result is an integer.

360÷20=18

360÷24=15

360÷45=8

360 is common multiple of the three numbers. And it is the LCM.