Lesson 5 — Activity 3:

Percent , Decimals, and Sales



Getting Ready


It is important to be able to flip back and forth between decimals and percents when solving everyday percent problems. For example, if we want to know the price of an item that is 20% off, we can easily use our calculator to solve the problem.

Try This:

If a watch is regularly $120, and it is on sale for 20% off, how much do you save?

Use your calculator and type in the following:

120 x .20



    120 x .20 = 24

    You would save $24, so the watch would cost $96 ($120 – $24 = $96)



To find out how much the percentage is when buying items, all you need to do is use the calculator on your phone and do the following:

1. Look at the percentage that is being discounted (e.g., 50%).

2. Change that number into a decimal (e.g., .50).

3. Take the regular price of the item and multiply it by the decimal amount (e.g., $120 x .50 = 60).

4. Subtract that number from the original price, and you will know how much the new price with the discount is (e.g., $120 – $60 = $60).


Let's try another example.

If a snowboard is regularly $480, and it is on sale for 30% off, how much do you save? What is the price of the snowboard with the discount? Use your calculator to figure out the answer.

$480 x .30 = $144
$480 – $144 = $336
The snowboard is on sale for $336.


Click here to try a Flash activity where you will practise working out the cost of items on sale.


  Self-check!

Try this!

Try this activity where you will practice figuring out the sales price based on a percentage


Percents are part of an everyday experience and conversation. On Boxing Day a lot of people head out shopping because of great sales. Here are some examples of some boxing day sales you could find:


If all video games were 30% off the original ticketed price, what would you save on a video game worth originally $60? How much would the game cost on sale?

Step 1: Change the percent (%) to a decimal first. You can do this by moving the decimal place two places to the left.

Therefore you have 0.30

Step 2: Then multiply this decimal by the original ticket price. Therefore you have 0.30 x 60 = 18

This means you saved $18.00.

Step 3: Now subtract the savings from the original ticket price. Therefore, you have 60 - 18 = 42

This means the game would cost $42.00 on sale.


If all DVD movies were 40% off the listed price, what would save on a DVD with a listed price of  $24? How much would the DVD cost on sale?

Step 1: Change the percent (%) to a decimal first. You can do this by moving the decimal place two places to the left.

Therefore you have 0.40

Step 2: Then multiply this decimal by the original ticket price. Therefore you have 0.40 x 24 = 9.6

This means you saved $9.60.

Step 3: Now subtract the savings from the original ticket price. Therefore, you have 24 - 9.6 = 14.4

This means the DVD would cost $14.40 on sale.