Everyday maths for Health and Social Care and Education Support 1
Everyday maths for Health and Social Care and Education Support 1

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 for Health and Social Care and Education Support 1

4.2 Calculations using decimals

When you make any calculation with decimals – that is, addition, subtraction, multiplication and division – you may use a calculator. When using a calculator it is very important to make sure that the decimal point is in the correct place. If you don’t, you’ll get the wrong answer.

Now try the following activity. Remember to check your answers once you have completed the questions.

Activity 13: Using decimals

Described image
Figure 19 Using decimals
  1. You buy a box of corn flakes for £2.65 and a bottle of milk for £1.98.
    • a.What is the total cost of these items?
    • b.You pay for them with a £5 note. How much change should you get?
  2. A patient’s height and weight are used to calculate their Body Mass Index (BMI). These measures are often decimal numbers.
    • a.What is the patient’s weight in the image above?
    • b.What is the patient’s height (in metres) in the image above? Multiply the height by itself.
    • c.Divide your answer to part a) by your answer to part b). This will tell you the BMI of the patient.
  3. Convert 6.25 m to cm.


  1. The answers are as follows:
    • a.Add the cost of the two items:

      The sum £2.65 + £1.98 = £4.93.

      (Keep the decimal points in line.)

      The total cost of the items is £4.63.

    • b.Take away the total cost from £5:

      The sum £5.00 – £4.63 = £0.37.

      You should get 37p change from £5.


    • a.The patient's weight is 40.5 kg
    • b.The patient’s height is 1.5 m. Therefore 1.5 × 1.5 = 2.25
    • c.40.5 ÷ 2.25 = 18.

    So the BMI of the patient is 18.

  3. To convert 6.25 m into cm, you need to multiply the amount by 100.

    • 6.25 × 100 = 625

    So the answer is 625 cm.


In this section you have learned about how:

  • the value of a digit depends on its position in a decimal number
  • to approximate answers to calculations involving decimal numbers
  • to add, subtract, multiply and divide using decimal numbers.

This will help when working with money and measurements.


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