Q: What are the prime factors of the number 21,000,100?

 A: 2, 5, 11, 17, 1123

Why are those the prime factors of the number 21,000,100?

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 21,000,100

21,000,100
Factor Arrows
210,500,050
Factor Arrows
25,250,025
Factor Arrows
51,050,005
Factor Arrows
5210,001
Factor Arrows
1119,091
Factor Arrows
171,123

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, 11, 17, 1123

We can check our work by multiplying all of the prime factors together: 2 x 2 x 5 x 5 x 11 x 17 x 1,123 = 21,000,100

This can also be written as 22 x 52 x 111 x 171 x 1,1231 = 21,000,100

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


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