Question

What is the GCF for 15 35 and 20

Answer 1

15 = 3 * 5

35 = 5 * 7

and 

20 = 2 * 2 * 5

so GCF = 5

Answer 2

The greatest common factor, or GCF for short, is the biggest number that all of true numbers go into (this is a factor). To find the GCF, list out all of the factors 15, 20, and 35 go into.

15)

1, 3, 5, 15

20)

1, 2, 4, 5, 10, 20

35)

1, 5, 7, 35

The biggest factor that 25, 20, and 35 go into is 5. The GCF of these numbers is five