Q: What are the prime factors of the number 39,904?

 A: 2, 29, 43

Why are those the prime factors of the number 39,904?

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 39,904

39,904
Factor Arrows
219,952
Factor Arrows
29,976
Factor Arrows
24,988
Factor Arrows
22,494
Factor Arrows
21,247
Factor Arrows
2943

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, 29, 43

We can check our work by multiplying all of the prime factors together: 2 x 2 x 2 x 2 x 2 x 29 x 43 = 39,904

This can also be written as 25 x 291 x 431 = 39,904

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


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