Question

Determine the greatest common factor for the pair of numbers.

28, 40
Select one:
A. 16
B. 8
C. 4
D. 28

Answer 1

The greatest common factor is 4.  28 is not divisible by 16 and not divisible by 8.  40 is not divisible by 28.  28 and 40 are divisible by 4 however.  28 divided by 4 is 7.  40 divided by 4 is 10.  Therefore the answer is C.. 4

Answer 2

Answer: C

Step-by-step explanation:

     28                 40

      ∧                   ∧

     4 7               4 10

     ∧                 ∧   ∧

    2 2              2 2 2 5

28: 2 * 2 * 7

40: 2 * 2 * 2 * 5

What do they have in common?  two 2s

GCF: 2 * 2 = 4