# How do you write the sum of the number 63+15 as the product of their GCF and another sum?

Oct 18, 2016

$63 + 15 = 3 \times \left(21 + 5\right)$

#### Explanation:

The prime factors of $63$ are $3 \times 3 \times 7$

and those of $15$ are $3 \times 5$

As only $3$ is common, GCF is $3$

and as such $63 + 15$ can be written as

$63 + 15 = 3 \times 21 + 3 \times 5 = 3 \times \left(21 + 5\right)$