Working with Percentages

We are now moving away from decimals and looking at percentages. We need to know a few little tricks for working with percentages.

The first thing we need to know how to do find a percentage from a small set taken out of a whole. For example, you need to know how to find what percentage say 18 out of a group of 50 is.
The easiest way I have found to do this is to make a fraction with our small set as the numerator (top number) and the whole group as our denominator (bottom number).

So in the example above we would have the fraction 18/50, because 18 is our smaller set and 50 is our total group. 

Next, we use our conversion skills to convert the fraction into a percentage. To do this we divide our numerator by our denominator, then multiply this new number by 100. If you do not know how to do this, see a previous post titled "Converting between fraction, decimals, and percentages". 

So for the example above, we would have

18 ÷ 50 = 0.36 x 100 = 36%

We now know that 18 out of 50 is 36%

The next skill we need is finding a number from a given percentage. So for example, I may want to find what 27% of 500 is. 

To do this, we first convert the percentage to a decimal, and then multiply this by our whole group. So for the example above, we would convert 27% to a decimal (by dividing by 100), which gives us 0.27. Next we would multiply this new decimal by our whole group (500). This gives us: 

0.27 x 500 = 135

We now know that 27% of 500 is 135. 

These are the first two skills (and probably the most important skills) when working with percentages. 

To practice these skills, go through the following worksheet. For now just work through the first page of questions. You can access the worksheet by clicking here, or it can also be found in the "Worksheets" tab. 

As always, if you have any questions, feel free to comment on this post, or email or chat to me in person.