How To: Do Prime Factorization

What Is Prime Factorization?

Prime factorization is finding prime numbers that, when multiplied, equal the original number.

Method

The best and easiest way to do prime factorization is to use a factor tree.

Step 1:

In this example, we will look for the prime factorization of 90. Using a factor tree, we will find all of the prime numbers that when multiplied, equal 90, and circle them. The prime factors of 90 are 2, 3, 3, and 5.

Step 2:

Now that you've found how the prime numbers, you now you have the prime factorization of 90. All you have to do is put it into correct form. The answer to the prime factorization of 90 is : 90 = 2 • 3 • 3 • 5

But, a better way to put it is : 90 = 2 • 3² • 5

Prime Factorization of Prime Numbers

If a number is already prime, the prime factorization of that number is itself. For example, the prime factorization of 13 = 13 because 1 and 13 are the only prime numbers that can be divided evenly by 13.

Practice Time

1. What is the prime factorization of 19?

2. What is the prime factorization 22?

3. What is the prime factorization of 30?

4. What is the prime factorization of 60?

Answers:

1. The prime factorization of 19 = 19

2. The prime factorization of 22 = 2 • 11

3. The prime factorization of 30 = 2 • 3 • 5

4. The prime factorization of 60 = 2² • 3 • 5

For more practice, play this game! Click the link to play the game : http://www.mangahigh.com/en_us/games/sigmaprime

Step 3:

If this information was somehow confusing, you can watch this video to get a better understanding of prime factorization :

https://www.youtube.com/watch?v=ZKKDTfHcsG0

Citations

http://www.mathsisfun.com/prime-factorization.html