Percents
Calculating Percentages
Calculating percent problems
There are many times in real life when you may need to calculate a percentage. You might need to figure out how much money a 5% discount will save you, or how much interest you'll pay on a loan with a 6% interest rate. Knowing how to calculate percentages will help you in both of these situations.
Setting up the calculation
Let's say the mailing department was responsible for 25% of the accidents at your company this year. There were 80 accidents total, and 20 of them were in the mailing department. You could write that like this:
25% of 80 = 20
This expression tells you that 25% of 80 is equal to 20. But what if you don't know how much a percentage is equal to? Let's say the demolition department was responsible for 50% of the 80 accidents. You don't know how many accidents 50% of 80 is. So you could write that like this:
50% of 80 = ?
To figure out what 50% of 80 is, you'll need to rewrite this example so it can be solved with math.
Click through the slideshow to see how to set up the example as a mathematical expression.
Set these examples up as mathematical expressions. Don't try to solve them yet!
90 people work at your office. 85% of them work in computers. You want to know how many people work in computers.
There are 300 children at your child's school. 17% of them failed their state tests. How many students failed their tests?