Listing:

List the factors until you find a common one.

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

24: 1, 2, 3, 4, 6, 8, 12, 24

GCF= 6

Prime factors:

Find the prime factorization of each.Circle the common digits between the two. Multiply the common digits and that is your GCF

36: 2x2x3x3

42: 2x3x7

2x3=6

GCF=6 Listing:

List until you find common multiples

2: 2, 4, 6, 8, 10, 12

3: 3, 6, 9, 12

4: 4, 8, 12

Prime factorization:

Figure out the prime factorization of each. Cross out common digits. Multiply the remaining numbers of the smaller digit times the bigger number out of the two.

Ex:

8: 2x2x2

14: 7x2

LCM= 2x2x14= 56

=56 ;