LESSON: Prime Factorization

READ: Classify Given Numbers as Prime or Composite

Now that you have learned all about identifying and finding factors, we can move on to organizing numbers. We can put numbers into two different categories. These categories are prime and composite. The number of factors that a number has directly affects whether or not the number is considered a prime number or a composite number.

What is a prime number?

Prime numbers are special numbers. As you can see in the text box, a prime number has only two factors. You can only multiply one and the number itself to get a prime number.

Example

Think about 13. Is it a prime number?

Yes. You can only get thirteen if you multiply 1 and 13. Therefore it is prime.

Here is a chart of prime numbers.

Notice that 1 has a next to it. One is neither prime nor composite.

What is a composite number?

A composite number is a number that has more than two factors. Most numbers are composite numbers. We can see from the chart that there are 25 prime numbers between 1 and 100. The rest are composite because they have more than two factors.