Everyday maths 2
Everyday maths 2

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

Free course

Everyday maths 2

5.1 Calculating a percentage of an amount

Working out the percentage of an amount requires a similar method to finding the fraction of an amount. Take a look at the examples below to increase your confidence.

Example: Finding 17% of 80

Method

17% of 80 = 17 divided by 100 of 80, so we do:

80 ÷ 100 × 17 = 13.6

Example: Finding 24% of 60

Method

24% of 60 = 24 divided by 100 of 60, so we do:

60 ÷ 100 × 24 = 14.4

Just as with fractions, you will often need to be able to work out the price of an item after it has been increased or decreased by a given percentage. The process for this is the same as with fractions; you simply work out the percentage of the amount and then add it to, or subtract it from, the original amount.

Activity 9: Percentages of amounts

  1. You earn £500 per month. You get a 5% pay rise.
    • a.How much does your pay increase by?
    • b.How much do you now earn per month?

Answer

  1.  

    • a.5% of £500 = five divided by 100 of £500 = 500 ÷ 100 × 5 = £25.
    • b.£500 + £25 = £525 per month.

  1. You buy a new car for £9,500. By the end of the year its value has decreased by 20%.
    • a.How much has the value of the car decreased by?
    • b.How much is the car worth now?

Answer

  1.  

    • a.20% of £9500 = 20 divided by 100 of £9500 = £9500 ÷ 100 × 20 = £1900. The car has decreased by £1900.
    • b.The car is now worth: £9500 − £1900 = £7600.
  1. You invest £800 in a building society account which offers fixed-rate interest at 4% per year.
    • a.How much interest do you earn in one year?
    • b.How much do you have in your account at the end of the year?

Answer

  1.  

    • a.4% of £800 = four divided by 100 of £800 = £800 ÷ 100 × 4 = £32 interest earned.
    • b.£800 + £32 = £832 in the account at the end of the year.

There are two other skills that relate to percentages that are very useful to know. The first is percentage change. This can be useful for working out the percentage profit (or loss) or finding out by what percentage an item has increased or decreased in value.

FSM_2

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to University-level study, we offer two introductory routes to our qualifications. You could either choose to start with an Access module, or a module which allows you to count your previous learning towards an Open University qualification. Read our guide on Where to take your learning next for more information.

Not ready for formal University study? Then browse over 1000 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus371