Q: What are the prime factors of the number 123,840?

 A: 2, 3, 5, 43

Why are those the prime factors of the number 123,840?

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 123,840

123,840
Factor Arrows
261,920
Factor Arrows
230,960
Factor Arrows
215,480
Factor Arrows
27,740
Factor Arrows
23,870
Factor Arrows
21,935
Factor Arrows
3645
Factor Arrows
3215
Factor Arrows
543

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, 43

We can check our work by multiplying all of the prime factors together: 2 x 2 x 2 x 2 x 2 x 2 x 3 x 3 x 5 x 43 = 123,840

This can also be written as 26 x 32 x 51 x 431 = 123,840

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


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