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MATH MENTOR: Finding percentages - Part 2

To review, you may go to Percentages Part 1

Remember: when you work with percentages,

WHOLE = 100%

Finding the Part

When you calculate amounts with percentages, you must express the percentage as a decimal. For example,

• 50% is calculated as 0.50 or .50

• 25%  is calculated as 0.25 or .25
• 10% is calculated as 0.10 or .10
• 75% is calculated as 0.75 or .75 and so on

In Part I, you multiplied the whole by the percentage to find the part.

W x % = P

or

or

Finding the Whole

What if you don't know the whole, or the 100% amount? Look at the following example:

12 workers at Pitfall Road Service, or 15% of all employees, received a bonus for their teamwork and cooperation on the job. How many people are employed?

It doesn't say. But you do know that 12 workers = 15% or .15

To find the whole when you know only the parts, change the process. Of course!

P / % = W

12 ÷  .15 = 80 The total number of employees is 80.

Are you sure? Test it with your first formula!

% x W = P .15 X 80 = 12. There you have it.

So here's another formula to help you work with percentages.

Try your hand at providing the whole number from the percentage and part given. You can do it! Remember - P / % = W

Example: P = 560  560 = 15% so 552 / .15 = 3,680

1. 670 = 25%

ANSWER 670/.25 = 2680

2. 55,800 = 35%  

ANSWERS 55,800 / .30 = 186,000

3.1,640 = 75%  

ANSWER 1,640 / .75 = 2186.66.. rounded to 2186.7

Now you have two images to record into your memory.

Close this page to return to your unit. If you want, you may also, continue to learn one more formula for working with percentages!