Q: What are the prime factors of the number 3,920?

 A: 2, 5, 7

Why are those the prime factors of the number 3,920?

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 3,920

3,920
Factor Arrows
21,960
Factor Arrows
2980
Factor Arrows
2490
Factor Arrows
2245
Factor Arrows
549
Factor Arrows
77

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, 5, 7

We can check our work by multiplying all of the prime factors together: 2 x 2 x 2 x 2 x 5 x 7 x 7 = 3,920

This can also be written as 24 x 51 x 72 = 3,920

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


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