How to decrease an amount by a percentage

Part of MathsPercentages

Key points

  • An amount can be decreased by a in different ways:

    • By working out the decrease and subtracting it from the original value.

    • By considering the resulting overall percentage and using a .

  • To be able to decrease an amount by a percentage, you need to be able to work out percentages of an amount, convert percentages to decimals and decimals to percentages.

  • Identifying multipliers is a useful technique to use for this method. Processing calculations in one step can save time.

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Calculate the percentage decrease and subtract from original amount

To decrease an amount by a given percentage:

  1. Work out the percentage of the amount. There are different ways to do this, choose your preferred method:

a. Combining other percentages. For example, 20% is two lots of 10%

b. Using equivalent fractions. For example 20% is the same as 1⁄5

c. Using a calculator. For example to work out 20% divide 20 by 100 and multiply by the amount.

  1. Subtract from the original amount.

Examples

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  1. Written: Decrease sixty by twenty percent. Below: A bar shaded orange – labelled sixty. A bar split in five blocks with the one shaded purple and labelled twenty percent of sixty. The final bar is the first orange bar with a section the size of the purple block cut off the end.

    To decrease 60 by 20%, work out 20% of 60, then subtract it from the original amount (60)

Question

Decrease 50 by 30%

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How to decrease an amount by a percentage using a multiplier

To decrease an amount by a percentage using a :

  1. The original amount is 100%.

  2. Subtract the percentage the amount is being decreased by to get the remaining percentage.

  3. Convert the remaining percentage value to a decimal by dividing by 100. This is the multiplier.

  4. Multiply the original amount by the multiplier.

Examples

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  1. Example 1: Decrease sixty by twenty percent.

    Decrease 60 by 20%

Question

Decrease 800 by 24%

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Practise how to decrease an amount by a percentage

Practise how to decrease an amount by a percentage in this quiz.

Quiz

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Real-world maths

A white person tying their shoelaces on a pair of black trainers
The discount on a pair of trainers gives the actual saving. Subtracting the discount from the original price gives the sale price.

As part of a membership to a leisure centre, members are able to get a percentage discount at a sports shop. The price a member has to pay will be the original price decreased by a percentage. For example, if the discount is 20%, a pair of trainers priced at £90 will be £72 (100% – 20% = 90 – 18)

Healthy eating and drinking trends have led to many food companies reducing the sugar content in their products by a percentage. This enables them to produce healthier products and retain their sales.

A white person tying their shoelaces on a pair of black trainers
The discount on a pair of trainers gives the actual saving. Subtracting the discount from the original price gives the sale price.
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Game - Divided Islands

Using your maths skills, help to build bridges and bring light back to the islands in this free game from BBC Bitesize.

Play the Divided Islands game!
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More on Percentages

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