Q: What is the prime factorization of the number 231,138?

 A:
  • The prime factors are: 2 x 3 x 3 x 12,841
    • or also written as { 2, 3, 3, 12,841 }
  • Written in exponential form: 21 x 32 x 12,8411

Why is the prime factorization of 231,138 written as 21 x 32 x 12,8411?

What is prime factorization?

Prime factorization or prime factor decomposition is the process of finding which prime numbers can be multiplied together to make the original number.

Finding the prime factors of 231,138

To find the prime factors, you start by dividing the number by the first prime number, which is 2. If there is not a remainder, meaning you can divide evenly, then 2 is a factor of the number. Continue dividing by 2 until you cannot divide evenly anymore. Write down how many 2's you were able to divide by evenly. Now try dividing by the next prime factor, which is 3. The goal is to get to a quotient of 1.

If it doesn't make sense yet, let's try it...

Here are the first several prime factors: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29...

Let's start by dividing 231,138 by 2

231,138 ÷ 2 = 115,569 - No remainder! 2 is one of the factors!
115,569 ÷ 2 = 57,784.5 - There is a remainder. We can't divide by 2 evenly anymore. Let's try the next prime number
115,569 ÷ 3 = 38,523 - No remainder! 3 is one of the factors!
38,523 ÷ 3 = 12,841 - No remainder! 3 is one of the factors!
12,841 ÷ 3 = 4,280.3333 - There is a remainder. We can't divide by 3 evenly anymore. Let's try the next prime number
12,841 ÷ 5 = 2,568.2 - This has a remainder. 5 is not a factor.
12,841 ÷ 7 = 1,834.4286 - This has a remainder. 7 is not a factor.
12,841 ÷ 11 = 1,167.3636 - This has a remainder. 11 is not a factor.
...
Keep trying increasingly larger numbers until you find one that divides evenly.
...
12,841 ÷ 12,841 = 1 - No remainder! 12,841 is one of the factors!

The orange divisor(s) above are the prime factors of the number 231,138. If we put all of it together we have the factors 2 x 3 x 3 x 12,841 = 231,138. It can also be written in exponential form as 21 x 32 x 12,8411.

Factor Tree

Another way to do prime factorization is to use a factor tree. Below is a factor tree for the number 231,138.

231,138
Factor Arrows
2115,569
Factor Arrows
338,523
Factor Arrows
312,841

More Prime Factorization Examples

231,136231,137231,139231,140
25 x 311 x 23311811 x 1,2771371 x 6,247122 x 51 x 71 x 131 x 1271

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