Find the greatest common factor of 18 and 45?

Answer 1

(A) Fully factorise both numbers:

So 18 = 2*3*3 and 45 = 3*3*5

(B) For the gcf write down only those numbers (factors) that appear in both factorisations. If they appear twice in both factorisations, write them twice for the gcf.

So here we have gcf = 3*3

[there is no 2 in the factorisation of 45 so no 2 in the gcf. Likewise, no 5 because it is not there for 18.]

(C) Multiply the numbers in the gcf together so gcf = 9.

Answer 2

The factors of 18 are:

1, 2, 3, 6, 9, 18

The factors of 45 are:

1, 3, 5, 9, 15, 45

The common factors are:

1, 3, 9

The Greatest Common Factor:

GCF = 9

Answer 3

18:1,2,3,6,9,18

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

in 18 & 45 there is the nine for the highest

Answer 4

The least common factor of any set of positive integers is 1.

Answer 5

The GCF is 9.

Answer 6

The GCF is 9.

Answer 7

9