# How do you find the greatest common factor of 68, 34?

Dec 3, 2016

$G C F = 2 \times 17 = 34$

#### Explanation:

Write each number as the product of its prime factors then you can see what you are working with:

$\text{ "34 = 2 xx " } 17$
$\text{ } \underline{68 = 2 \times 2 \times 17}$
$G C F = \text{ "2 " } \times 17 = 34$

{notice that the GCF is the product of all the common factors.]

You could have known this immediately if you realise
that 34 is half of 68.