Calculate the Greatest Common Factor or GCF of 20, 40, 45 and 80
Sponsors
The instructions to find the GCF of 20, 40, 45 and 80 are the next:
1. Decompose all numbers into prime factors
| 20 | 2 |
| 10 | 2 |
| 5 | 5 |
| 1 |
| 40 | 2 |
| 20 | 2 |
| 10 | 2 |
| 5 | 5 |
| 1 |
| 45 | 3 |
| 15 | 3 |
| 5 | 5 |
| 1 |
| 80 | 2 |
| 40 | 2 |
| 20 | 2 |
| 10 | 2 |
| 5 | 5 |
| 1 |
2. Write all numbers as the product of its prime factors
| Prime factors of 20 | = | 22 . 5 |
| Prime factors of 40 | = | 23 . 5 |
| Prime factors of 45 | = | 32 . 5 |
| Prime factors of 80 | = | 24 . 5 |
3. Choose the common prime factors with the lowest exponent
Common prime factors: 5
Common prime factors with the lowest exponent: 51
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 = 51 = 5
Also calculates the: