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

Answer:

c)360

Step-by-step 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.