# Complete the Calculation Practice 1

In this practice exercise, students will complete a calculation by adding in the missing number so that both sides are equal. They will need to follow the rules of BIDMAS. It will strengthen their number skills.

Key stage:  KS 2

Curriculum topic:   Exam-Style Questions: Verbal Reasoning

Curriculum subtopic:   Exam-Style Questions: Complete the Calculation

Difficulty level:

### QUESTION 1 of 10

If you are unsure of an answer move on to the next question.  You should come back to questions you found difficult at the end if you have time.

Look at the following calculation:

7 + 5 x 3 = 10 x 2 + ( __ )

Both sides of the calculation must be equal.

We need to work out the answer to the left side of the calculation before we can work out the mystery number on the right side of the calculation.

We must follow the rules of BIDMAS (or BODMAS) in these calculations.

When you complete a calculation using BIDMAS, you answer anything in brackets first, then any indices (squared and cubed numbers),  then the division and multiplication parts, followed by the addition and subtraction parts.

Following the rules of BIDMAS, we must calculate 5 x 3 first and then add 7. This gives us 22.

So the answer on the right must equal 22. 10 x 2 is 20 so the mystery number must be 2 to make a total of 22.

7 + (5 x 3) = (10 x 2)+ 2

Now it's time to begin this practice exercise.  Good luck!

Below is a calculation, where both sides should be equal.

However, one of the numbers has been taken away by the cheeky number burglar! Can you work out what it is?

Remember to follow the rules of BIDMAS!

99 + 70 - 17 =  __ + 7² x 3

15

3

5

7

10

Are you up for another one, number detective?

Below is a calculation where both sides should be equal.

Can you find out what number is missing?

Remember to follow the rules of BIDMAS!

78 + 56 - 13 = __ + 9² + 23

7

11

13

15

17

Below is another calculation where both sides should be equal.

Can you find out what the mystery number is?

Remember to follow the rules of BIDMAS!

56 + 120 ÷ 2 = __ + 9 x 12

18

8

10

9

11

Are you ready for another challenge, number detective?

Below is a calculation where both sides should be equal.

Can you find the missing number?

Remember to follow the rules of BIDMAS!

67 + 250 ÷ 2 = __² + 92

10

12

15

17

20

You're halfway through already, number detective!

Below is a calculation where both sides should be equal.

Can you find out what number has been missed out?

Remember to follow the rules of BIDMAS!

492 + 1² -  250 = 150 x 2 - __

56

58

53

57

59

Are you finding these are getting any easier, number detective?

Below is a calculation where both sides should be equal.

Can you use your detecting skills to find the mystery number?

Remember to follow the rules of BIDMAS!

200 - 32 + 34 =  __ x 12 - 10

6

8

10

12

14

Are you coping with these challenging questions? Don't worry if you're finding them hard - the more you practise, the easier they will become.

Below is a calculation where both sides should be equal.

Can you find the missing number?

Remember to follow the rules of BIDMAS!

104 + 34 + 202 = __ + 5² + 250

62

64

65

66

67

Below is a calculation where both sides should be equal.

Can you find the mystery number?

Remember to follow the rules of BIDMAS!

119 - 37 + 55 = __ + 7 x 9

70

74

84

54

64

Only two more questions to go, number detective - don't give up now!

Below is a calculation where both sides should be equal.

Can you find what number has been missed out?

Remember to follow the rules of BIDMAS!

140 ÷ 2 x 3 = __ + 4 x 15

15

50

125

120

150

Well done, number detective - you have reached the final question!

Below is yet another calculation where both sides should be equal!

Can you spot what number has been missed out?

Remember to follow the rules of BIDMAS!

173 + 5 x 100 = __ + 60 x 6

115

311

313

315

331

• Question 1

Below is a calculation, where both sides should be equal.

However, one of the numbers has been taken away by the cheeky number burglar! Can you work out what it is?

Remember to follow the rules of BIDMAS!

99 + 70 - 17 =  __ + 7² x 3

5
EDDIE SAYS
Well, what did you make of this first one?! Don't worry if you took one look and wanted to run away! These questions can look very challenging, but if you work through them, step by step, using the rule of BIDMAS, you will find them much less scary. So, we start with the left-hand side - the only operations on this side are addition and subtraction and we know from the BIDMAS rule that addition comes first. This means the first sum is 99 + 70, which gives us 169. Next, you need to subtract 17 from this to get 152 as the total for the left side. Now we need to follow the BIDMAS order for the right-hand side. There are no brackets but there are indices, so the first thing to do is to work out 7², which is 7 x 7 = 49. Then, you multiply: 49 x 3 = 147. Lastly, find the difference between 147 and 152 by counting on. Did you follow all those steps? Don't worry if it seems a lot to do - it will become easier with practice.
• Question 2

Are you up for another one, number detective?

Below is a calculation where both sides should be equal.

Can you find out what number is missing?

Remember to follow the rules of BIDMAS!

78 + 56 - 13 = __ + 9² + 23

17
EDDIE SAYS
Did you find this one any easier, detective? Remember that we work through it in stages, starting with the left-hand side. Here, the first operation to do is ADDITION: 78 + 56 = 134. Next, we have to subtract 13 from this to give us 121 as the total on the left-hand side. To find the missing number and get the same total on the right, you need to follow BIDMAS order, which means that the first thing we have to do is 9², which is 9 x 9 = 81. After that, we simply need to add: 81 + 23 = 104 before finally, finding the difference between 121 and 104 by doing 121 - 104. How did you get on - is it beginning to make sense?
• Question 3

Below is another calculation where both sides should be equal.

Can you find out what the mystery number is?

Remember to follow the rules of BIDMAS!

56 + 120 ÷ 2 = __ + 9 x 12

8
EDDIE SAYS
Are you beginning to get the hang of these yet, number detective? Starting with the left-hand side, division comes before addition in the BIDMAS order, so the first thing to do is 120 ÷ 2 = 60. After that, you can add 56 to the number to give a total of 116 on the left-hand side. To get the same on the right-hand side of the calculation, do 9 x 12 = 108. Then, find the difference between 108 and 116 by counting forwards. Let's try another one!
• Question 4

Are you ready for another challenge, number detective?

Below is a calculation where both sides should be equal.

Can you find the missing number?

Remember to follow the rules of BIDMAS!

67 + 250 ÷ 2 = __² + 92

10
EDDIE SAYS
A bit of a tricky one but don't panic! Start as you would with all the other questions and work out the left-hand side first. Look at the operations on the left side - division comes before addition in the BIDMAS order, so the first thing to do is: 250 ÷ 2 = 125. Next, you need to add 67 to this to give the total of 192 on the left side. To solve the right side of the calculation, you would normally have to complete the squared number first (indices come before addition in the BIDMAS order), but as you don't know what it is, you have to work backwards, First, do 192 - 92 = 100. Only then can we work out what number multiplied by itself equals 100. We know that 10 x 10 = 100, so that is our answer. Well done if you got all that, number detective!
• Question 5

You're halfway through already, number detective!

Below is a calculation where both sides should be equal.

Can you find out what number has been missed out?

Remember to follow the rules of BIDMAS!

492 + 1² -  250 = 150 x 2 - __

57
EDDIE SAYS
OK, let's break it down! Starting on the left, the first operation to do is indices. A top tip here is that it doesn't matter how many times you multiply 1 by itself, it will always equal 1 - so 1 squared gives us the answer 1! Now, we need to add 492 and 1, before subtracting 250 from the result. This gives us the total of 243 on the left-hand side. To solve the right-hand side, you do 150 x 2 = 300. Finally, do the sum 300 - 242, which gives us 57. Fantastic!
• Question 6

Are you finding these are getting any easier, number detective?

Below is a calculation where both sides should be equal.

Can you use your detecting skills to find the mystery number?

Remember to follow the rules of BIDMAS!

200 - 32 + 34 =  __ x 12 - 10

12
EDDIE SAYS
How did you get on with this challenging question, detective! Let's take the left-hand side first - addition comes before subtraction, so we do: 32 + 34 = 66. Next, you have to subtract this from 200 to give the total of 134 for the left-hand side. To solve the right side of the calculation, you would normally start with the multiplication. However, as there is a number missing from this part, you have to work backwards to find it. Do 134 + 10 = 144. Then work out what number multiplied by 12 equals 144, and you have your answer of 12. Terrific work, number detective!
• Question 7

Are you coping with these challenging questions? Don't worry if you're finding them hard - the more you practise, the easier they will become.

Below is a calculation where both sides should be equal.

Can you find the missing number?

Remember to follow the rules of BIDMAS!

104 + 34 + 202 = __ + 5² + 250

65
EDDIE SAYS
I bet you found the left hand side a bit of a treat to do! Since they are all addition sums, it doesn't matter what order you do them in, and you get a total of 340 for the left side. To solve the right side of the calculation, first do the indices (5 squared): 5 x 5 = 25. Then the addition: 25 + 250 = 275. Finally, you need to find the difference between 340 and 275 by doing 340 - 275. Hopefully, these are becoming a bit easier for you now.
• Question 8

Below is a calculation where both sides should be equal.

Can you find the mystery number?

Remember to follow the rules of BIDMAS!

119 - 37 + 55 = __ + 7 x 9

74
EDDIE SAYS
Did you find out what the missing number is? This one was a bit tricky because you needed to put brackets into the left-hand side before you could do the calculation: (119 - 37) + 55. This means that you had to do the subtraction in the brackets first to get 82, and then add the 55 back on to make a total of 137 on the left-hand side. To solve the right-hand side of the calculation, first do 7 x 9 = 63, and then finally, do the sum 137 - 63, which gives you 74. Excellent work!
• Question 9

Only two more questions to go, number detective - don't give up now!

Below is a calculation where both sides should be equal.

Can you find what number has been missed out?

Remember to follow the rules of BIDMAS!

140 ÷ 2 x 3 = __ + 4 x 15

150
EDDIE SAYS
Let's take it a step at a time, as usual. On the left-hand side, the first operation to do is DIVISION because division comes before multiplication in the BIDMAS order. So, we do: 140 ÷ 2 = 70. Next, we use multiplication to do the sum: 70 x 3 = 210, which is the total for the left side. For the second part, you start off with 4 x 15 (which you can do as 15 x 4 if it's easier) = 60. Then, find the difference between 210 and 60 by doing 210 - 60. This gives the answer 150! Now let's see what the last question is, detective!
• Question 10

Well done, number detective - you have reached the final question!

Below is yet another calculation where both sides should be equal!

Can you spot what number has been missed out?

Remember to follow the rules of BIDMAS!

173 + 5 x 100 = __ + 60 x 6

313
EDDIE SAYS
OK, let's go through it! On the left side, multiplication comes first: 5 x 100 = 500. Next, we need to add 173 to this to make a total of 673 on the left-hand side. To solve the second part of the calculation, you start off by doing 60 x 6 = 360. Then, all that is needed is to find the difference between 673 and 360 which means doing the sum 673 - 360. Hooray, you have completed this activity! Hopefully, you are feeling more confident with these questions now, but if you want some more practice, there are two other worksheets of this level of difficulty for you to have a go at.
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