What is the highest common factor of 63 and 18?

Answer 1

To find the highest common factor (hcf) of 2 numbers you need to consider the list of factors for each number.

Finding factors is easier if you think about them in pairs (the two factors that have the original number as their product) and start with the lowest first (i.e. 1 and itself then consider 2, 3 etc.)

Factors of 34 are:

1 and 34; 2 and 17

The factors of 63 are:

1 and 63; 3 and 21; 7 and 9

Now identify any numbers that are in both lists of factors - these are common factors and the highest value one is the hcf. In this case there is only one cf so 1 is the hcf of 34 and 63.

Answer 2

The GCF of 33 and 63 is 3.

The prime factorization of 33 is 3*11.

The prime factorization of 33 is 3*3*7

The GCF is 3.

Answer 3

The GCF is 1.

Answer 4

The GCF is 7.

Answer 5

The GCF is 9.

Answer 6

GCF(33, 63) = 3

Answer 7

7

Answer 8

It is: 9