We can convert a percentage to a decimal number by dividing by #100#.

Therefore, #5\%=\dfrac{5}{100}=5:100=0.05#.

Examples

#28\%=0.28#

#77\%=0.77#

When we convert percentages to decimals, we can calculate how much a particular #\blue{\text{percentage}}# is of a #\green{\text{number}}#.

For example, #\blue{28}\%# of #\green{2600}# equals: #0.28 \times \green{2600}=728#.

In general, we can state the following:

To calculate a certain #\blue{\textit{percentage}}# of a #\green{\textit{number}}#, we calculate:

#\frac{\blue{\textit{percentage}}}{100} \times \green{\textit{number}}#

Example

How much is #\blue{59}\%# of #\green{600}#?

\[\begin{array}{rcl}\\ \dfrac{\blue{59}}{100} \times \green{600}&=&0.59 \times \green{600} \\ &=& 354\end{array}\]

We also want to be able to calculate what percentage a specific #\blue{\text{part}}# is of a specific #\green{\text{whole}}#. Suppose we have a group of #\green{79}# people. #\blue{19}# people have blue eyes, and we want to know what percentage of the group has blue eyes.

The entire group of #\green{79}# people equals #100\%#.

Therefore, #1# person is #\frac{1}{\green{79}}\times 100\% \approx 1.27\%#.

To calculate what percentage #\blue{19}# people is, we multiply #\frac{1}{\green{79}}\times 100\%# by #\blue{19}#. Therefore, #\blue{19}# of #\green{79}# equals: #\frac{\blue{19}}{\green{79}} \times 100 \%\approx 24.05\%#

In general, we can state:

To calculate what percentage a specific #\blue{\textit{part}}# is of a specific #\green{\textit{whole}}#, we calculate:

#\frac{\blue{\textit{part}}}{\green{\textit{whole}}} \times 100\%#

Examples

\[\begin{array}{rcl}\blue{18} &\text{ of} & \green{29} \\&\text{ equals }& \\ \dfrac{\blue{18}}{\green{29}} \times 100\% &\approx& 62.1\% \\ \\ \\ \\ \blue{52} &\text{ of }&\green{128}\\&\text{ equals }& \\\dfrac{\blue{52}}{\green{128}} \times 100\% &\approx &40.6\%\end{array}\]