# What is the LCM of 9 and 42?

Apr 3, 2016

$126$

#### Explanation:

An alternative method to find the LCM is to find the GCF (greatest common factor) and divide the product of the numbers by it.

To find the GCF of two numbers you can proceed as follows:

Divide the larger number by the smaller to give a quotient and remainder.

If the remainder is zero then the smaller number is the GCF.

Otherwise, repeat with the smaller number and the remainder.

In our example:

$\frac{42}{9} = 4$ with remainder $6$

$\frac{9}{6} = 1$ with remainder $3$

$\frac{6}{3} = 2$ with remainder $0$

So the GCF of $42$ and $9$ is $3$

So the LCM is $\frac{42 \cdot 9}{3} = 42 \cdot 3 = 126$