Investigate and Calculate Percentage Discounts of 10, 25 and 50 on Sale Items (6)

Investigate and calculate percentage discounts of 10%, 25% and 50% on sale items, with and without digital technologies (ACMNA132)

LO: To calculate percentage discounts of 10%, 25% and 50%.

Know:

  • What a percentage represents.

Understand:

  • That percentages discount means saving money.

Do:

    • I can calculate percentage discounts of 10, 25 and 50% from the original price of an item.

Essential Questions:

  • What is a percentage?

  • Why is a percentage always out of 100?

Calculating Discounts

One thing to always remember the word ‘per cent’ comes from Latin per centum, which means per hundred. Which is why a percentage is always out of 100.

100% of an item means paying full price.
50% means paying half of the full price.
25% means paying a quarter (half then half again) of the full price.
10% means paying a tenth (divide by 10) of the full price.

1% means paying a hundreth (divide by 100) of the full price.

Visual Representations

One technique to help in understanding percentages is using a bar model. In the picture above, it shows how 30% can be represented as part of a whole.

Step-by-Step Process

1) Find the percent discount and change it into a decimal value or a fraction. eg.) 20% means 0.2 or 20/100

2) Since the full price is 100% of the price, you want to find a certain amount of the full amount so you multiply the full amount by the decimal or fraction value in step 1.

3) The answer given will the be discounted amount.

4) To figure out the final price you have to subtract the discounted amount from the original amount.

Worked Example

To calculate discount, we have to first figure out how much money do we save with the discount.

The first step is to find out what 25% of $14.99 is, so what we do is $14.99 x 25/100 (25 out of 100 is the same as 25%).

We figured out that $3.75 is 25% of $14.99, which means we save $3.75.

When leaving the store I would have to pay $14.99 – $3.75 = $11.24

ACARA Work Sample

Interactives

Percentage Discount Videos

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