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

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

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

  • What a percentage is.
  • The four basic operations of numeracy

Understand:

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

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 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 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