How do you write the fraction 9/21 in simplest form?

Nov 28, 2016

$\frac{3}{7}$

Explanation:

$\frac{9}{21} = \frac{\cancel{3} \times 3}{\cancel{3} \times 7} = \frac{3}{7}$

Nov 28, 2016

$\frac{3}{7}$

Explanation:

We have to find a $\textcolor{b l u e}{\text{common factor}}$ that will divide into both 9 and 21 and reduce the fraction.

In this case the lowest common factor is $\textcolor{red}{3}$

rArr9/21=(9÷3)/(21÷3)=3/7

This is usually written as shown below.

$\frac{9}{21} = {\cancel{9}}^{3} / {\cancel{21}}^{7} = \frac{3}{7} \leftarrow \textcolor{red}{\text{ in simplest form}}$

This process is called $\textcolor{b l u e}{\text{cancelling}}$

A fraction is in $\textcolor{red}{\text{simplest form}}$ when no other factor apart from 1 will divide into the numerator/denominator.