# What is the GCF of 30 and 45?

Sep 6, 2016

15

#### Explanation:

'Splitting' the numbers down into their prime factors giving:

$30 \to 2 \times \textcolor{red}{3} \textcolor{w h i t e}{\times 3} \times \textcolor{b l u e}{5}$
$45 \to \textcolor{w h i t e}{2 \times} \textcolor{red}{3} \times 3 \times \textcolor{b l u e}{5}$

The common values are: $3 \times 5 = 15$

So the GCF = 15

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You will find a list of prime numbers on any search engine. I would suggest that 'images' may be a better search option.