Calculate the Greatest Common Factor or GCF of 42, 45, 56 and 70
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The instructions to find the GCF of 42, 45, 56 and 70 are the next:
1. Decompose all numbers into prime factors
| 42 | 2 |
| 21 | 3 |
| 7 | 7 |
| 1 |
| 45 | 3 |
| 15 | 3 |
| 5 | 5 |
| 1 |
| 56 | 2 |
| 28 | 2 |
| 14 | 2 |
| 7 | 7 |
| 1 |
| 70 | 2 |
| 35 | 5 |
| 7 | 7 |
| 1 |
2. Write all numbers as the product of its prime factors
| Prime factors of 42 | = | 2 . 3 . 7 |
| Prime factors of 45 | = | 32 . 5 |
| Prime factors of 56 | = | 23 . 7 |
| Prime factors of 70 | = | 2 . 5 . 7 |
3. Choose the common prime factors with the lowest exponent
Common prime factors: None
Common prime factors with the lowest exponent: None
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.
Since there are not common prime factors the GCF is 1
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