Q: What are the prime factors of the number 39,900?

 A: 2, 3, 5, 7, 19

Why are those the prime factors of the number 39,900?

Prime factors are the prime numbers that can be multipled together to equal the original number. You find the factors by dividing by prime numbers. It is best shown by creating a Factor Tree.

Factor Tree for the number 39,900

39,900
Factor Arrows
219,950
Factor Arrows
29,975
Factor Arrows
33,325
Factor Arrows
5665
Factor Arrows
5133
Factor Arrows
719

The numbers in bold above are the prime factors. If there are multiples, you only count them one time. This leads us to our prime factors of:

2, 3, 5, 7, 19

We can check our work by multiplying all of the prime factors together: 2 x 2 x 3 x 5 x 5 x 7 x 19 = 39,900

This can also be written as 22 x 31 x 52 x 71 x 191 = 39,900

If you would like to know more, or need additional explanation, please review our prime factorization explanation.


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