# Solve the Calculation Using BIDMAS

In this worksheet, 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:   Verbal Reasoning

Curriculum subtopic:   Complete the Calculation

Difficulty level:

### QUESTION 1 of 10

Calling all number detectives!

Look at this symbol:

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:

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

Remember to follow the rules of BIDMAS.

It’s now your turn to complete the calculation! Good luck!

Below is a calculation where both sides should be equal.

Can you work out what the missing number is?

Remember to follow the rules of BIDMAS!

94 + 350 ÷ 10 = __ + 20 x 2

Ready for another one, number detective?

Below is a calculation where both sides should be equal.

Can you work out what the missing number is?

Remember to follow the rules of BIDMAS!

101 + 55 x 2 = __ + 11 x 11

Here's another one to get your teeth into, 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!

90 x 2 - 96 = 70 ÷ 10 x __

Below is another calculation where both sides should be equal.

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

Remember to follow the rules of BIDMAS!

950 ÷ 10 x 2 = 60 x 4 - __

You're halfway through this activity already, 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!

123 + 77 -  60 = 35 x 2 x __

Guess what - another exciting chance to complete the calculation!

Below is a calculation where both sides should be equal.

Can you find the missing number?

Remember to follow the rules of BIDMAS!

88 + 27 + 13 = 20 x 8 - __

Keep going, number detective, you're nearly there!

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!

98 + 64 - 41 = __ + 14 x 5

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

Can you find the mystery number?

Remember to follow the rules of BIDMAS!

650 + 250 - 450 = __ + 100 x 3

Last two questions coming up, 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!

32 ÷ 2 x 4 = 16 ÷ 4 x __

Welcome to the last question, number detective!

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!

105 + 100 ÷ 10 = __ + 5 x 15

• Question 1

Below is a calculation where both sides should be equal.

Can you work out what the missing number is?

Remember to follow the rules of BIDMAS!

94 + 350 ÷ 10 = __ + 20 x 2

89
EDDIE SAYS
How did you get on with this first question? Did you remember to use BIDMAS to solve this calculation? Start with the left side and work through the order of operations - there are no brackets or indices, so the first operation to do is DIVISION: 350 ÷ 10 = 35. Next, you need to add 94 to this to get the total of 129 for the left side. To get the same total for the second part and find the missing number, you first do 20 x 2 = 40. Finally, you have to find the difference between 129 and 40 by doing 129 - 40, which equals 89. Great work, detective!
• Question 2

Ready for another one, number detective?

Below is a calculation where both sides should be equal.

Can you work out what the missing number is?

Remember to follow the rules of BIDMAS!

101 + 55 x 2 = __ + 11 x 11

90
EDDIE SAYS
Did you find the missing number, detective? Let's go through it slowly, step by step, so we can see exactly what to do. Start with the left side and go through, looking for the first operation to use from the BIDMAS rule. There are no brackets, indices or division, so the first operation to do is MULTIPLICATION: 55 x 2 = 110. Next, you need to add 101 to this to get the total of 211 for the left-hand side. To work out the part on the right, you do 11 x 11 = 121. Then, 211 - 121 which equals 90. Don't worry if you are still finding this tricky - practice will help you to become more confident.
• Question 3

Here's another one to get your teeth into, 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!

90 x 2 - 96 = 70 ÷ 10 x __

12
EDDIE SAYS
You're doing great! Let's start with the left-hand side and work through the BIDMAS rule. There are no brackets, indices or division, so the first operation to do is MULTIPLICATION: 90 x 2 = 180. Next, we need to subtract 96 from this number and we end up with the number 84 on the left-hand side. To get the same total on the right-hand side, we need to do the division first (because division comes before multiplication in BIDMAS), so we do the sum 70 ÷ 10 = 7. Finally, we need to find how many sevens there are in 84, which can be worked out by doing 84 ÷ 7 = 12.
• Question 4

Below is another calculation where both sides should be equal.

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

Remember to follow the rules of BIDMAS!

950 ÷ 10 x 2 = 60 x 4 - __

50
EDDIE SAYS
What a lot of numbers! Working through the BIDMAS rule on the left-hand side, we get to DIVISION: 950 ÷ 10 = 95. Next, we need to multiply 95 by 2, which gives us the total of 190 for the left side. For the second part, you need to do 60 x 4 = 240. Finally, you need to find the difference between 240 and 190 by doing 240 - 190 = 50.
• Question 5

You're halfway through this activity already, 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!

123 + 77 -  60 = 35 x 2 x __

2
EDDIE SAYS
How did you do with this one, number detective? Let's go through it, step by step. On the left side, the first operation to use is ADDITION because it comes before subtraction in the BIDMAS rule. So, we do the sum 123 + 77 = 200. Next, we have to subtract 60 from 200 to get the total of 140 for the left-hand side. To complete the second part of the calculation, you first do 35 x 2 = 70. Then, to work out how many seventies there are in 140, you do the sum 140 ÷ 70 = 2. Wow, you're halfway through this activity already!
• Question 6

Guess what - another exciting chance to complete the calculation!

Below is a calculation where both sides should be equal.

Can you find the missing number?

Remember to follow the rules of BIDMAS!

88 + 27 + 13 = 20 x 8 - __

32
EDDIE SAYS
Right, let's look at this one, step by step. On the left-hand side, the only operations are addition so we simply need to add all the three numbers together to make 128. A top tip to remember is that when adding numbers, it doesn't matter what order you add them in as you will reach the same total. For the second part of the sum, you do 20 x 8 = 160. Finally, you need to find the difference between 160 and 128 by doing the sum 160 - 128, which gives you 32! Terrific work if you got this one!
• Question 7

Keep going, number detective, you're nearly there!

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!

98 + 64 - 41 = __ + 14 x 5

51
EDDIE SAYS
Are you getting the hang of these yet, number detective? Start with the left-hand side and work through it, step by step. Addition comes before subtraction in the BIDMAS rule, so first, you need to add 98 and 64 to get 162. Next, you subtract 41 from this number to get 121 for the left-hand side. To solve the right-hand side of the calculation, you do 14 x 5 = 70 and finally, 121 - 70, which gives us the answer 51. Great work!
• Question 8

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

Can you find the mystery number?

Remember to follow the rules of BIDMAS!

650 + 250 - 450 = __ + 100 x 3

150
EDDIE SAYS
Did you find the missing number? First, you need to add 650 and 250 to get 900, and then subtract 450 to give the answer 450 on the left-hand side. Top tip: when adding blocks of hundreds you can remember the zeros then add them back again at the end. E.g. 650 + 250 would be 65 + 25 = 90. Then add the 0 back to make 900. For the second part of the sum, you first do 100 x 3 = 300. Then, you need to find the difference between the two numbers by doing the sum 450 - 300 = 150. Only two more to go - you're doing really well.
• Question 9

Last two questions coming up, 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!

32 ÷ 2 x 4 = 16 ÷ 4 x __

16
EDDIE SAYS
Lots of division to do in this question! Remember your BIDMAS rule and you will see that you need to divide before you multiply, so the first operation to do on the left side is 32 ÷ 2 = 16. Then, you need to multiply 16 by 4 to give you 64. This is the total for the left-hand side. To work out the second part of the calculation, you first do 16 ÷ 4 = 4 and finally, find how many fours there are in 64 by doing the sum 64 ÷ 4 = 16. One more number to find, let's take a look at the final question!
• Question 10

Welcome to the last question, number detective!

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!

105 + 100 ÷ 10 = __ + 5 x 15

40
EDDIE SAYS
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