Question

What is the greatest common factor of 84 and 21

Answer 1

21 is the Greatest Common Factor

Explanation:

First we write out the factors of 84 :

1,84

2,42

3,28

4,21

6,14

7,12

Now we write the factors of 21 :

1,21

3,7

The Greatest Common Factor (GCF) is the highest number that appears in both lists:

21 is the highest

So 21 is the GCF

Hope this helped and have a good day

Answer 2

The greatest commonest factor of these numbers can be found by firts writing out their factors.

84 = 1 x84, 2 x 42, 3 x 28, 4 x 21, 6 x 14, 7 x 12,

21 = 1 x 21, 3 x 7

So all the factors are

84 = 1, 2, 3, 4, 6, 7 , 12, 14, 21, 28, 42, 84

21= 1, 3, 7, 21

There it is clear that the greatest common factor is 21