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Add and Subtract Decimals

In this worksheet, students will practise adding and subtracting decimals in column method with a need to add zeroes to have the same number of decimal places.

'Add and Subtract Decimals' worksheet

Key stage:  KS 4

GCSE Subjects:   Maths

GCSE Boards:   Pearson Edexcel, OCR, Eduqas, AQA

Curriculum topic:   Number, Fractions, Decimals and Percentages

Curriculum subtopic:   Structure and Calculation, Decimal Fractions

Difficulty level:  

Worksheet Overview

QUESTION 1 of 10

When you are adding and subtracting decimals, there are two key things you need to do:

1) Line up your decimal points.

2) Fill in the decimals places, so there are the same amount in each question.

 

 

e.g. 4.75 + 2.4

 

Step 1: Set up the addition, taking care to line up your decimal points and add extra zeros where needed.

4.75
+  2.40
 

 

Step 2: Complete the addition as normal.

4.75
+  2.40
7.15

 

 

e.g. 3.845 - 0.48

 

Step 1: Set up the subtraction, taking care to line up your decimal points and add extra zeros.

3.845
-  0.480
 

 

Step 2: Complete the subtraction as normal.

3.845
-  0.480
3.365

 

 

Before you start this activity, grab a pen and paper so you can write out your own addition and subtraction sums to work them out. 

Work out:

 

2.5 + 0.3

 

Consider the sum:

 

20.42 + 0.8

 

Which number do you have to add zeros to?

20.42

0.8

Work out:

 

0.42 + 0.871

Think about the calculation:

 

21.751 + 3.82

 

How many decimal places will be in the answer?

Work out:

 

75.2 + 0.04

 

Calculate:

 

7.2 - 0.7

Consider this calculation:

 

31.7 - 0.5

 

Then complete the sentence below.

Look at the calculation:

 

38.5 - 0.56

 

Which of the sums below is in the correct format to work out this answer correctly?  

38.50 - 0.560

38.50 - 0.56

38.5 - 0.5

Calculate:

 

4.26 - 3.21

Finally, calculate:

 

10 - 4.67

  • Question 1

Work out:

 

2.5 + 0.3

 

CORRECT ANSWER
2.8
EDDIE SAYS
A nice easy one to start with, just ensure you line up the decimal points like this:
2.5
+    0.3
Then just add the columns as normal: 5 + 3 = 8 2 + 0 = 2 So our answer is 2.8!
  • Question 2

Consider the sum:

 

20.42 + 0.8

 

Which number do you have to add zeros to?

CORRECT ANSWER
0.8
EDDIE SAYS
Both numbers need to have the same number of decimal places before we start adding, so that we don't make any mistakes. As 0.8 is the shorter number with one decimal place, we have to add a zero to it so that both numbers have two decimal places.
  • Question 3

Work out:

 

0.42 + 0.871

CORRECT ANSWER
1.291
EDDIE SAYS
Here we need to add a zero to our shorter decimal (0.42) before we line up the numbers like this:
0.420
+    0.871
Then we can add the columns as normal. Did you spot a strange occurrence in the the third column? 4 + 8 = 12 So we need to carry the extra ten into the next column to the left. This means that our answer is 1.291 Did you spot that?
  • Question 4

Think about the calculation:

 

21.751 + 3.82

 

How many decimal places will be in the answer?

CORRECT ANSWER
3
EDDIE SAYS
The longest decimal has three decimal places, so the answer will have the same number. That's logical, isn't it? How could the answer have less or more decimal places than the question?
  • Question 5

Work out:

 

75.2 + 0.04

 

CORRECT ANSWER
75.24
EDDIE SAYS
We needed to add a 0 to 75.2 here, so that it had the same number of decimal places as 0.04. It seems strange to be adding to it as it is the larger number, but that's just the way it goes with this type of question!
75.20
+    0.04
  • Question 6

Calculate:

 

7.2 - 0.7

CORRECT ANSWER
6.5
EDDIE SAYS
Did you line up the decimals like our example below?
7.2
-    0.7
Then just add the columns as normal: 7 + 2 = 9 7 + 0 = 7 So our answer is 7.9 You've got this; keep going maths star!
  • Question 7

Consider this calculation:

 

31.7 - 0.5

 

Then complete the sentence below.

CORRECT ANSWER
EDDIE SAYS
Both numbers have been given to one decimal places already. This means that we don't need to add any extra zeroes to balance out the decimal places - phew! Questions like this are a gift, as they don't require as much brain power and are a good chance to save some time.
  • Question 8

Look at the calculation:

 

38.5 - 0.56

 

Which of the sums below is in the correct format to work out this answer correctly?  

CORRECT ANSWER
38.50 - 0.56
EDDIE SAYS
We need to change both numbers so that they have the same amount of decimal places. We can't just chop off a number or we will reach an inaccurate answer, so we have to add a zero onto the end of 38.5 so that it has 2 decimal places like 0.56. Does that make sense?
  • Question 9

Calculate:

 

4.26 - 3.21

CORRECT ANSWER
1.05
EDDIE SAYS
Did you set it out like this?:
4.26
-    3.21
There was no need to add any zeroes here, as both numbers had the same amount of decimal places.
  • Question 10

Finally, calculate:

 

10 - 4.67

CORRECT ANSWER
5.33
EDDIE SAYS
This is a tricky one, as we have to add 2 zeroes to our whole number so that it has the same number of decimal places as the other. Also, you can't borrow from the 0 so you have to go all the way across and borrow from the 1 of the ten. This means we have to do a lot of borrowing in this question! In the hundredths column, our sum is: 10 - 7 = 3 In the tenths column, it is: 9 - 6 = 3 In the units, it is: 9 - 4. We no longer have any tens, so our tens column has become irrelevant! How did you do with this one? Did you get 5.33? Well done if you did, if not, remember to work methodically through the steps. Why not review column addition or subtraction if you found this challenging?
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