# GCD4 Getting the GCD by Prime Factorization

In the **GCD2** and **GCD3**, we learned how to the the the Greatest Common Divisor (GCD) of two or more numbers by listing. In the video above, we introduce another method using prime factorization. In this method, we list the prime factors of the numbers, and then get the common divisors. The product of the prime factors is the GCD of the numbers.

**Practice **

Find the GCD of the following numbers using prime factorization.

1.) 12 and 18

2.) 14 and 35

3.) 27 and 33

4.) 16, 21, and 64

5.) 25, 50, and 100

The answers to the exercises above are available below this text. Answer the exercises above before scrolling. You may also want to proceed to the **next lesson** which is on getting the GCD of two or more numbers using prime factorization.

*Answers to Practice*

*1.) 6*

*2.) 7*

*3.) 3*

*4) 1*

*5.) 25*