Question

What is the greatest common factor of 16 and 40?

Answer 1

8

Explanation:

16 divided by 8 is 2.
40 divided by 8 is 5.
Neither of these can be reduced by any more common numbers, so therefore, 8 is your greatest common factor.

Answer 2

The GCF of 16 and 40 is 8.

Explanation:

Make a factor tree of each number:

1 - 16
2 - 8
4 - 4
8 -2
16 - 1

1 - 40
2 - 20
4 - 10
5 - 8
8 - 5
10 - 4
20 - 2
40 - 1

Answer 3

8

Explanation:

When doing GCF (Greatest Common Factor) questions, I like to do a prime factorization first:

`16=2xx2xx2xx2`
`40=2xx2xx2xx5`

For GCF, we want all the primes that are common to both our numbers. See that there are three 2's in both 16 and 40. We don't use the fourth 2 since only the 16 has that and we don't use the 5 because only the 40 has that. Therefore, the GCF is 8:

`8xx5=40`
`8xx2=16`