Division and Percentages:

Introduction to Percentages

A percentage tells us what part of a whole something is. The following video will explain what percentages mean and where they come from.

Video Source (05:35 mins) | Transcript

Percent literally means “out of 100,” or “compared to 100.” Percentages are written with the % symbol. If we have half of something it is the same as 50% because 50 is half of 100.

The practice problems in this section use the concept “out of 100” to help you visualize what is happening when we add or subtract a percentage from another amount. We will go into this in more detail in the next few mini-lessons.

Additional Resources

Khan Academy: The Meaning of Percent (03:00 mins, Transcript)

Practice Problems

What does a percent mean?
If an item purchased at a store costs $1 and has a sales tax rate of 6%, what will be the total amount paid for the item?
If a tire store is having a sale for 10% off any tire, and you purchase a tire that normally costs $100, what is the sale price of the tire after the 10% is taken off?
If you earn 20% commission for any sale you make, and you sell $100 worth of product, how much will you earn for that sale?
If you earn $100 and pay tithing at a rate of 10%, how much money will you pay in tithing?

Solutions

Out of 100
$1.06 (Solution Video | Transcript)
$90 (Written Solution)

100% represents the original price of the tire.

Since the tire is 10% off, we can subtract 10% from 100%. 100% − 10% = 90%;

so we will be paying 90% of the original price.

Since the original price is $100, we can follow the same pattern $100 − $10 = $90.
$20 (Solution Video | Transcript)
$10 (Written Solution)

100% represents your earnings. Tithing is 10% of what you earned; if you earn $100, then you would pay $10. In this situation the 90% = $90 of your earnings and 10% = $10 for tithing.

This 10 by 10 grid holds 100 squares, the blue represents tithing 10%, and the 90% represents the earning after tithing.