Question

L.C.M. of 5,8,12,20 will not be a multiple of
a)5
b)3
c)9
d)2​

Answer 1

9 will not be a multiple of the LCM of 5,8,12,20

Answer 2

Answer:

L.C.M. of 5,8,12,20 will not be a multiple of 9.

Option c is the correct answer.

Step-by-step explanation:

Here given numbers are 5,8,12,20.

We want to find here LCM of given numbers.

But now question is How can we find LCM?

LCM means Lowest Common Multiple.

By some examples,we can understand this concept easily.

Example 1:

25 and 35

First we are breaking these two numbers into prime numbers.

So,

$25 = 5 \times 5 \\ 35 = 5 \times 7$

Here lowest common multiple of 25 and 35 is (5×5×7)=175.

So LCM of 25 and 35 is 175.

Example 2:

38 and 19

First we are breaking these two numbers into prime numbers.

So,

$38 = 2 \times 19 \\ 19 = 19 \times 1$

Here lowest common multiple of 38 and 19 is $(2 \times 19) = 38$

So,LCM of 38 and 19 is 38.

Here given numbers are 5,8,12,20.

We are breaking these two numbers into prime numbers.

$5 = 5 \times 1 \\ 8 = 2 \times 2 \times 2 \\ 12 = 2 \times 2 \times 3 \\ 20 = 2 \times 2 \times 5$

Lowest common multiple of 5,8,12,20 is

$2 \times 2 \times 2 \times 3 \times 5 = 120$

Here LCM of 5,8,12,20 is 120.

We can see that In the given option 5,3,2 are multiple of 120 but 9 is not multiple of 120.