# How do you find the gcf 15 18 30?

Dec 20, 2016

The Greats Common Factor Is: $3$

#### Explanation:

First, simply list out the factors that will multiply to give us each of the numbers. See below:

$15$'s Factors Are: $3 \cdot 5$ and $15 \cdot 1$.

$18$'s Factors Are: $3 \cdot 6$ and $2 \cdot 9$ and $1 \cdot 18$.

$30$'s Factors Are: $3 \cdot 10$ and $1 \cdot 30$.

Now we have to ask ourselves, what number out of all three of these is the greatest common factor? All three of these numbers share a common factor and that is $3$. They do not share any other factor.

Therefore, the greatest common factor of all these numbers is $3$.

Answer: $3$.