How do you you work out the common factor?

Answer 1

All numbers have factors. Some numbers have some of the same factors as other numbers. These are known as common factors. If you compare the lists of factors, you will see which ones are common.
Example: 30 and 42
1, 2, 3, 5, 6, 10, 15, 30
1, 2, 3, 6, 7, 14, 21, 42

The common factors are 1, 2, 3, 6

Answer 2

One way is to list them.

The factors of 30 are:

1, 2, 3, 5, 6, 10, 15, 30

The factors of 42 are:

1, 2, 3, 6, 7, 14, 21, 42

The common factors are:

1, 2, 3, 6

Answer 3

Example: 30 and 42

Factor them.

2 x 3 x 5 = 30

2 x 3 x 7 = 42

Select the common factors.

2 x 3 = 6, the GCF

Answer 4

Factor two numbers. Example: 30 and 42

2 x 3 x 5 = 30

2 x 3 x 7 = 42

Select the common factors.

2 x 3 = 6, the GCF