Relationship between H.C.F and L.C.M of Two Numbers

Preview

The relationship between H.C.F and LCM is really easy to find once you get the point. So for example if we have the two numbers 6 and 9 we first have to find the LCM of each of the two numbers then the H.C.F of each number as well:

6= 6, 12, 18, 24, 30

9=9, 18, 27, 36, 45

LCM=18

6=2 x 3

9=3 x 3

HCF=3

So now we know that the LCM of 6 and 9 is 18 and the HCF of 6 and 9 is 3 so the theory is that:

LCM=18 

HCF=3

=6x9=54 and 18x3=54

Now try some of these and make sure to watch the video on YouTube.

Sheet 1 What is the Relationship between HCF and LCM

How to Find L.C.M by Prime Factorization Method

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There's a lot of ways to find the LCM of a number but in this lesson I am going to be teaching you how to find LCM with prime factors. Now to do that you will have to make prime factorization trees for the two numbers. So lets take the two numbers 4 and 8 and lets make two trees:

                               4                          8

                            2 x 2                     2 x 4

                                                           2 x 2

So the factors for each numbers are :

4= 2 x 2

8= 2 x 2 x 2 

So to find the LCM all we have to do is find the first common factor which is 2 so the LCM of the two numbers 4 and 8 is 2.
Now try some of these and make sure to watch the video on YouTube.

Sheet 1 LCM by Prime Factorization Method