Calculate the Greatest Common Factor or GCF of 12, 21, 30 and 51
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The instructions to find the GCF of 12, 21, 30 and 51 are the next:
1. Decompose all numbers into prime factors
12 | 2 |
6 | 2 |
3 | 3 |
1 |
21 | 3 |
7 | 7 |
1 |
30 | 2 |
15 | 3 |
5 | 5 |
1 |
51 | 3 |
17 | 17 |
1 |
2. Write all numbers as the product of its prime factors
Prime factors of 12 | = | 22 . 3 |
Prime factors of 21 | = | 3 . 7 |
Prime factors of 30 | = | 2 . 3 . 5 |
Prime factors of 51 | = | 3 . 17 |
3. Choose the common prime factors with the lowest exponent
Common prime factors: 3
Common prime factors with the lowest exponent: 31
4. Calculate the Greatest Common Factor or GCF
Remember, to find the GCF of several numbers you must multiply the common prime factors with the lowest exponent.
GCF = 31 = 3
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