Question

What is the gcf for 18 and 84

Answer 1

The method is to figure out the prime factorization:
18 / 2 = 9
9 / 3 = 3
3 / 3 = 1

2 x 3 x 3 = 18

42 / 2 = 21
21 / 3 = 7
7 / 7 = 1

2 x 3 x 7 = 42

84 / 2 = 42
42 / 2 = 21
21 / 3 = 7
7 / 7 = 1

2 x 2 x 3 x 7 = 84

Look at each factorization and figure out which numbers appear in all the factorizations:
2 x 3 x 3 = 18
2 x 3 x 7 = 42
2 x 2 x 3 x 7 = 84

The common factors are 2 and 3:
2 x 3 = 6

Answer:
GCF(18, 42, 84) = 6

P.S. Double-check that all are divisible by 6:
18 / 6 = 3
42 / 6 = 7
84 / 6 = 14

Answer 2

This is not m work