Solve Problems Involving the use of Percentages, Including Percentage Increases and Decreases (8)

Solve problems involving the use of percentages, including percentage increases and decreases, with and without digital technologies(ACMNA187)

LO: To calculate the percentage increase/decrease of a quantity.

Know:

  • What percentage represents.

  • The four basic operations of numeracy.

  • An increase means in addition to the original amount.

  • A decrease means a reduction to the original amount.

Understand:

  • That a number or amount can be increased/decreased by a certain value.

Do:

  • I can calculate the percentage increase/decrease of a quantity.

Percentage Increase/Decrease

100% of an item means the full number or full amount.

Percentage increase means to increase your original number, which means that the final number should be larger than the original number.

To find the percentage increase, you have to first find the amount you want to increase the original amount by, then add that to your original amount.

For example, if I want to increase by 20% to $80.

First, I would need to find out what is 20% of 80. So I can use the multiplication method, which is 0.20 (20% in decimal form) multiplied by 80. which gives me $16. Since I’m increasing it from $80, I would add $16 + $80 which is $96.

Percentage decrease means to decrease from your original number, which means that the final number should be smaller than the original number.

Conversely, to find percentage decrease, you have to first find the amount you want to decrease the original amount by, then subtract from your original amount.

For example, if I want to decrease $80 by 20%.

First I would find what is 20% of 80, which is 0.2 multiplied by 80, which is 16.

Since this is percentage decrease, I would subtract 16 from 80. 80 -16 = $64.

Percentage Increase/Decrease Videos