Finding GCF and LCM Using Prime Factorization

Subtraction method

Multiplication method

Factor trees

Division method

3 and 8

4 and 6

2 and 12

5 and 5

2, 2, 3, 3

2, 2, 2, 3

3, 3, 2

2, 3, 4

2 x 2 x 3

3 x 3 x 3

2 x 3 x 3

2 x 2 x 3 x 3

To save time

To find the GCF and LCM more easily

To make the numbers look neat

To avoid mistakes

18

6

12

8

By adding the prime factors

By multiplying all the prime factors

By matching and multiplying only the common prime factors

By subtracting the prime factors

Adding the prime factors

Multiplying all the prime factors

Stretching the prime factorization of 36

Ignoring the unmatched factors

48

84

60

72

By subtracting the prime factors

By using all the prime factors, including unmatched ones

By adding the prime factors

By using only the common prime factors