Q: What are the prime factors of the number 647,640?

 A: 2, 3, 5, 7, 257

Why are those the prime factors of the number 647,640?

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 647,640

647,640
Factor Arrows
2323,820
Factor Arrows
2161,910
Factor Arrows
280,955
Factor Arrows
326,985
Factor Arrows
38,995
Factor Arrows
51,799
Factor Arrows
7257

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, 257

We can check our work by multiplying all of the prime factors together: 2 x 2 x 2 x 3 x 3 x 5 x 7 x 257 = 647,640

This can also be written as 23 x 32 x 51 x 71 x 2571 = 647,640

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


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