The Common Factor Calculator lists every factor shared by a set of whole numbers, along with their greatest common factor.
| Common factors | 1, 3, 5, 15 |
| Greatest common factor | 15 |
| Factors of 330 | 1, 2, 3, 5, 6, 10, 11, 15, 22, 30, 33, 55, 66, 110, 165, 330 |
| Factors of 75 | 1, 3, 5, 15, 25, 75 |
| Factors of 450 | 1, 2, 3, 5, 6, 9, 10, 15, 18, 25, 30, 45, 50, 75, 90, 150, 225, 450 |
| Factors of 225 | 1, 3, 5, 9, 15, 25, 45, 75, 225 |
A common factor divides each number in a set exactly. For 330, 75, 450 and 225 the common factors are 1, 3, 5 and 15. All common factors are themselves factors of the greatest common factor.
Find the GCF first (here 15), then list its factors. This is faster than listing every factor of every number.
Common factors help simplify fractions and ratios, split groups evenly and factor algebraic expressions (taking out a common factor).
Is 1 always a common factor? Yes.
What if the only common factor is 1? The numbers are relatively prime.
Can negative numbers be used? Their factors are the same as the positive values.