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Find the Missing Number to Complete the Sum

In this worksheet, students will complete a calculation by adding in the missing numbers. It will strengthen their number skills.

'Find the Missing Number to Complete the Sum' worksheet

Key stage:  KS 2

Curriculum topic:  Verbal Reasoning

Curriculum subtopic:  Complete the Calculation

Difficulty level:  

Worksheet Overview

QUESTION 1 of 10

Calling all number detectives!

 

Look at this symbol:

 

equals sign

 

We know it is the equals sign but what does it actually mean?

It means the same as and doesn’t just mean the answer.

 

Look at the following calculation:

19 = 7 + __

One of the numbers is missing.

So 19 is the same as 7 add something.

Now we have two options, we can count on from 7 to 19 or take away 7 from 19 to work out the missing number.

Following either of these options, we find that the missing number is 12.

19 = 7 + 12


 

Let’s try another:

17 = 20 - __

In this question, the answer of 17 is the same as 20 take away something.

What do we need to take away from 20 to reach 17?

The missing number is 3.

17 = 20 - 3

 

Pssstt!! Here’s a handy hint to help you reach superstar status:

Remember that equals means the same as and the answers on either side of the equals sign must be the same.


 

In this activity, you will be completing sums by finding the missing number.

Good luck!

 

Let's get started then!

Below is a calculation. One of the numbers has been taken away by the cheeky number burglar! Can you work out what it is, number detective? 

 

__ = 8 x 5

 

Burglar with light

 

Ready for another one?

Below is a calculation. One of the numbers has been taken away by the cheeky number burglar! Can you work out what it is, number detective? 

 

__ = 28 - 14

 

Are you getting the idea now?

Below is another calculation. One of the numbers has been taken away by that irritating number burglar! Can you work out what it is number detective? 

 

__ = 24 + 11

 

Let's try another one, number detective!

Below is a calculation. One of the numbers has been taken away. Can you work out what the number is?

 

__ = 12 x 5

 

You're halfway through this activity already, number detective!

Below is yet another calculation! One of the numbers is missing - can you work out what it is?

 

__ = 39 - 12

 

Let's keep going - you've not got many more to do to complete this activity.

One of the numbers in this calculation is missing. Can you work out what it is, number detective? 

 

__ = 11 x 2

 

Can you work out what number is missing from the calculation below, number detective?

 

__ = 34 + 14

 

You're nearly there!

Can you work out what number is missing from the calculation below? 

 

__ = 11 x 10

 

Only two more questions to go, number detective!

Below is another calculation. What number has been missed out this time

 

__ = 25 + 15

 

 

The final question in this activity!

What number has been taken away from the calculation below - can you work it out, number detective?

 

__ = 47 - 13

 

  • Question 1

Let's get started then!

Below is a calculation. One of the numbers has been taken away by the cheeky number burglar! Can you work out what it is, number detective? 

 

__ = 8 x 5

 

Burglar with light

 

CORRECT ANSWER
40
EDDIE SAYS
How did you do with this first question? Did you remember that equals means 'the same as'? All we have to do is find something that is the same as 8 x 5. Counting in fives! Eight lots of five makes 40.
  • Question 2

Ready for another one?

Below is a calculation. One of the numbers has been taken away by the cheeky number burglar! Can you work out what it is, number detective? 

 

__ = 28 - 14

 

CORRECT ANSWER
14
EDDIE SAYS
Did you get this one, number detective? You needed to find a number that is the same as 28 - 14. What method did you use? One way is to separate the number into tens and units. So 28 - 10 = 18. Then 18 - 4 = 14. There are several ways you could have found the answer - you need to use the one that works best for you.
  • Question 3

Are you getting the idea now?

Below is another calculation. One of the numbers has been taken away by that irritating number burglar! Can you work out what it is number detective? 

 

__ = 24 + 11

 

CORRECT ANSWER
35
EDDIE SAYS
Are you getting the hang of these? Did you work out the answer? You can add the tens, then the units. So 24 + 10 = 34. Then 34 + 1 = 35. This is the correct answer because 35 is the same as 24 + 11.
  • Question 4

Let's try another one, number detective!

Below is a calculation. One of the numbers has been taken away. Can you work out what the number is?

 

__ = 12 x 5

 

CORRECT ANSWER
60
EDDIE SAYS
Counting in fives this time! Twelve groups of five makes sixty. Top tip: all numbers in the five times tables end in either a 5 or a 0. So, you have your correct answer because 60 is the same as 12 x 5.
  • Question 5

You're halfway through this activity already, number detective!

Below is yet another calculation! One of the numbers is missing - can you work out what it is?

 

__ = 39 - 12

 

CORRECT ANSWER
27
EDDIE SAYS
You're whizzing through these! Remember what the equals sign means - the same as. So, what is the same as 39 - 12? You can subtract the tens first: 39 - 10 = 29. Then the units: 29 - 2 = 27. And you have your answer - brilliant!
  • Question 6

Let's keep going - you've not got many more to do to complete this activity.

One of the numbers in this calculation is missing. Can you work out what it is, number detective? 

 

__ = 11 x 2

 

CORRECT ANSWER
22
EDDIE SAYS
How did you do with this one? Did you remember that you need to find out what is the same as 11 x 2? Simply use your two times table to work this one out, remembering that all numbers in the two times tables end in an even number!
  • Question 7

Can you work out what number is missing from the calculation below, number detective?

 

__ = 34 + 14

 

CORRECT ANSWER
48
EDDIE SAYS
This time, you have an addition sum to work out. First you can add the tens: 34 + 10 = 44. Then the units: 44 + 4 = 48. This gives you the correct answer because 48 is the same as 34 + 14.
  • Question 8

You're nearly there!

Can you work out what number is missing from the calculation below? 

 

__ = 11 x 10

 

CORRECT ANSWER
110
EDDIE SAYS
Did you find the missing number? The question is asking you to find the number that is the same as 11 x 10. When you multiply a number by 10, you need to add a zero to the number, so that gives us the answer 110.
  • Question 9

Only two more questions to go, number detective!

Below is another calculation. What number has been missed out this time

 

__ = 25 + 15

 

 

CORRECT ANSWER
40
EDDIE SAYS
Did you get this one? It is an addition sum this time. You can add the tens first: 25 + 10 = 35. Then the units: 35 + 5 = 40. One question to go, let's see what it is!
  • Question 10

The final question in this activity!

What number has been taken away from the calculation below - can you work it out, number detective?

 

__ = 47 - 13

 

CORRECT ANSWER
34
EDDIE SAYS
Did you get this final one right? It is asking you what is the same as 47 - 13. There are several ways you could work this out but one way to do it in your head is to think of it as tens and units. You can subtract the tens first: 47 - 10 = 37. Then the units: 37 - 3 = 34. What a legend, you've located all the missing numbers!
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