21 , 45

Find the common factors for the numerical part:

21,45

The factors for 21 are all numbers between 1 and 21, which divide 21 evenly.

Check numbers between 1 and 21

Find the factor pairs of 21 where x⋅y=21.

xy12137

List the factors for 21.

1,3,7,21

1,3,7,21

The factors for 45 are all numbers between 1 and 45, which divide 45 evenly.

Check numbers between 1 and 45

Find the factor pairs of 45 where x⋅y=45.

xy14531559

List the factors for 45.

1,3,5,9,15,45

1,3,5,9,15,45

List all the factors for 21,45 to find the common factors.

21: 1,3,7,21

45: 1,3,5,9,15,45

The common factors for 21,45 are 1,3.

1,3

The GCF (HCF) of the numerical factors 1,3 is 3.

3

Find the GCF 21 , 45