GCSE Maths Number FDP Decimals

Subtracting decimals

Subtracting Decimals

Here we will learn about subtracting decimals including how to solve problems that involve the subtraction of decimal numbers.

There are also subtracting decimals worksheets with word problems and problem solving questions based on Edexcel, AQA and OCR exam questions, along with further guidance on where to go next if you’re still stuck.

What is subtracting decimals?

Subtracting decimals involves using column addition to subtract decimal numbers by lining up the digits so that they have the same place value. 

The ones, decimal points, tenths, hundredths etc. should be lined up. This is particularly important to do if the values we are adding have been given to a different number of decimal places. 

This column method of subtraction only works if the number we are subtracting is smaller than the one we are subtracting it from. If we know our answer will be negative, we must switch the numbers around, find the positive difference and then make our answer negative.

What is subtracting decimals?

What is subtracting decimals?

How to subtract decimals

In order to subtract decimals:

  1. Set up a column subtraction, writing the larger number above the other. Make sure the decimal points line up to ensure numbers in each column have the correct place value. Fill in any gaps with zeros.
  2. Subtract each column from right to left remembering to exchange (or borrow) from the left if required.
  3. Read off your answer, remembering to include the decimal point. If the original subtraction would have given a negative answer, remember to include the negative sign.

How to subtract decimals

How to subtract decimals

Subtracting decimals worksheet

Get your free subtracting decimals worksheet of 20+ questions and answers. Includes reasoning and applied questions.

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Subtracting decimals worksheet

Get your free subtracting decimals worksheet of 20+ questions and answers. Includes reasoning and applied questions.

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Subtracting decimals examples

Example 1: Subtracting numbers with one decimal place

Work out 7.32.8.

  1. Set up a column subtraction, writing the larger number above the other. Make sure the decimal points line up to ensure numbers in each column have the correct place value. Fill in any gaps with zeros.

2Subtract each column from right to left remembering to exchange (or borrow) from the left if required.

3Read off your answer, remembering to include the decimal point. If the original subtraction would have given a negative answer, remember to include the negative sign.

The answer is 4.5.

Example 2: subtracting numbers with two decimal places

Work out 12.437.81.

The answer is 4.62.

Example 3: subtracting numbers with different amounts of decimals places

Work out 9.13.276.

The answer is 5.824.

Example 4: subtracting larger decimal numbers from smaller decimal numbers

Work out 4.367.21.

This subtraction will give a negative answer. We will need to swap the order to make the column subtraction method work. So we will work out 7.214.36, and make our answer negative later.

We swapped the order of the numbers in our subtraction so we need to make our answer negative.

The answer is −2.85.

Example 5: subtracting more than one decimal number from another

Find the change from £20 if items costing £3.47 and £11.79 are purchased.

We could do two separate subtractions or add the two items to be subtracted and subtract the total from £20.

Here we will add the two items and then set up one subtraction.

The answer is £4.74.

Common misconceptions

  • Not lining up the decimal point

A common error when subtracting decimals occurs when the decimal points are not lined up but instead the last digits are lined up.

E.g.

  • Not swapping the order when taking a larger number from a smaller number

It is important to remember that the column subtraction method does not give the correct answer if it is used with a smaller number above a larger number. If it is clear that the answer will be negative, we must remember to swap the order of the numbers for the subtraction and then make the answer negative.

Practice subtracting decimals questions

1. Work out 12.5  −  7.8

4.7
GCSE Quiz True

5.3
GCSE Quiz False

20.3
GCSE Quiz False

5.7
GCSE Quiz False

You must remember to line up the decimal points carefully and exchange (or borrow) from the left if required.

2. Work out 56.29  −  2.47

 3.159 
GCSE Quiz False

31.59
GCSE Quiz False

53.82
GCSE Quiz True

54.22
GCSE Quiz False

You must remember to line up the decimal points carefully and exchange (or borrow) from the left if required.

3. Work out 23.4  −  16.573

16.339
GCSE Quiz False

7.173
GCSE Quiz False

6.827
GCSE Quiz True

7.827
GCSE Quiz False

You must remember to line up the decimal points carefully, filling in any gaps with zeros. Exchange (or borrow) from the left if required.

4. Work out 3.51  −  8.29

4.78
GCSE Quiz False

-5.32
GCSE Quiz False

5.32
GCSE Quiz False

-4.78
GCSE Quiz True

You must remember to swap the order of the numbers to perform column subtraction, then put a negative sign on the answer.

5. Work out 8.5  −  1.4  −  5.9

4
GCSE Quiz False

1.2
GCSE Quiz True

2.8
GCSE Quiz False

2
GCSE Quiz False

Either add 1.4 and 5.9 together first and then subtract from 8.5 , or subtract 1.4 from 8.5 and then 5.9 from the answer.

6. Work out 11.2  −  3.6  −  2.01

9.61
GCSE Quiz False

5.5
GCSE Quiz False

6.13
GCSE Quiz False

5.59
GCSE Quiz True

Either add 3.6 and 2.01 together first and then subtract from 11.2 , or subtract 3.6 from 11.2 and then 2.01 from the answer.

Subtracting decimals GCSE questions

1.

a) Work out 12.79  −  5.82
 
b) Work out 44.6 – 23.39 – 8.42
 

(3 marks)

Show answer

a)

Correct answer of 6.97

(1)

 

b)

21.21 or 36.18 or 31.81 seen

(1)

Correct answer of 12.79

(1)

2. Complete the following calculations:

a)

b)


 

(5 marks)

Show answer

a)
 
9 in the top row.

(1)

 

3 in the second row.

(1)

 

b)
 
9 in first box in top row.

(1)

4 in second box in top row.

(1)

8 in second row.
 

(1)

3. Mark went to a clothes shop and bought 2 t-shirts costing £8.99 each, a hat costing £6.50 and a pair of shoes costing £22.90.

He paid for the items with a £50 note.

What change should he receive?

(3 marks)

Show answer

£8.99 + £8.99 + £6.50 + £22.90

(1)

 
£50 – £47.38.

(1)

Correct answer of £2.62.

(1)

Learning checklist

You have now learned how to:

  • Understand and use place value for decimals, measures and integers of any size
  • Use the four operations, including formal written methods, applied to integers, decimals, proper and improper fractions, and mixed numbers, all both positive and negative

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