Q: What are the prime factors of the number 77,760?

 A: 2, 3, 5

Why are those the prime factors of the number 77,760?

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 77,760

77,760
Factor Arrows
238,880
Factor Arrows
219,440
Factor Arrows
29,720
Factor Arrows
24,860
Factor Arrows
22,430
Factor Arrows
21,215
Factor Arrows
3405
Factor Arrows
3135
Factor Arrows
345
Factor Arrows
315
Factor Arrows
35

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

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 3 x 3 x 3 x 5 = 77,760

This can also be written as 26 x 35 x 51 = 77,760

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


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