Missing Numbers in Subtraction—Let's Practise!
- What Does it Mean to Find Missing Numbers in Subtraction?
- Missing Numbers in Subtraction – Example
- Missing Numbers in Subtraction – Guided Practice
- Missing Numbers in Subtraction – Application
- Missing Numbers in Subtraction – Examples
- Missing Numbers in Subtraction – Summary
- Missing Numbers in Subtraction – Frequently Asked Questions
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Basics on the topic Missing Numbers in Subtraction—Let's Practise!
Missing Numbers in Subtraction – Introduction
Get ready because today we're going to practise missing numbers in subtraction. It’s a great way to understand subtraction better by finding the missing number in a number sentence. Ready to begin? Let's go!
What Does it Mean to Find Missing Numbers in Subtraction?
Finding the missing number in subtraction means working out which number is missing from the subtraction equation to make it true.
For example, if you have the equation 15 - ? = 8, you can find the missing number by solving 15 - 8. Let’s practise this with some fun problems!
Missing Numbers in Subtraction – Example
Let's solve a problem by finding the missing number in subtraction:
Problem
15 - ? = 8
Solution
Follow these simple steps to find the solution.
| Step | Explanation | Result |
|---|---|---|
| Rewrite the number sentence | Move 8 before the equals sign | 15 - 8 = ? |
| Solve the new equation | 15 - 8 | 7 |
| Check your answer | Put 7 in the original equation | 15 - 7 = 8 |
So, 15 minus 7 equals 8!
Missing Numbers in Subtraction – Guided Practice
Let's try another problem together.
Problem
20 - ? = 12
So, 20 minus 8 equals 12!
Missing Numbers in Subtraction – Application
Now, try solving this problem on your own:
Problem ? - 5 = 9
So, 14 minus 5 equals 9!
Missing Numbers in Subtraction – Examples
To help yourself become fluent in finding missing numbers in subtraction, take a look at some more examples and complete them by following the steps.
| Problem | Rewrite the Equation | Solve the Equation | Check Your Answer | Solution |
|---|---|---|---|---|
| 18 - ? = 9 | 18 - 9 = ? | 18 - 9 = 9 | 18 - 9 = 9 | 9 |
| 14 - ? = 7 | 14 - 7 = ? | 14 - 7 = 7 | 14 - 7 = 7 | 7 |
| ? - 4 = 6 | 4 + 6 = ? | 4 + 6 = 10 | 10 - 4 = 6 | 10 |
| ? - 3 = 5 | 3 + 5 = ? | 3 + 5 = 8 | 8 - 3 = 5 | 8 |
Missing Numbers in Subtraction – Summary
Key Learnings from this Text:
- Finding the missing number in subtraction helps us understand subtraction better by completing the number sentence.
- Rewrite the equation to make solving easier.
- Solve the new equation to find the missing number.
- Check your answer by substituting it back into the original equation.
Keep practising finding missing numbers in subtraction to become a maths whiz! Check out more fun maths problems and activities on our website, such as subtraction using a number line, subtraction by counting on or using place value to subtract. Feel free to apply your skills and knowledge of subtraction and apply that to problem-solving with subtraction.
Missing Numbers in Subtraction – Frequently Asked Questions
Missing Numbers in Subtraction—Let's Practise! exercise
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What's the missing number?
HintsTo rewrite the equation, swap 32 with the missing number.
To find the missing number, solve 45 - 32.
Solution45 - ? = 32
45 - 32 = ?
45 - 32 = 13. 13 is the missing number.
Check your work. Put 13 back into the original equation. 45 - 13 = 32.
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Find the missing number.
HintsRewrite the equation.
- Swap the missing number with 16.
- When the missing number is first in the original equation, change the operation sign to +.
Solve the new equation
- What is 16 + 21?
- Put the answer into the original equation to check your work.
SolutionThe missing number is 37.
- Rewrite the equation as 16 + 21 = ?
- Solve the new equation by adding 16 + 21 = 37.
- Check your work. Put the missing number, 37, into the original equation. 37 - 21 = 16.
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Find the missing numbers.
HintsStep 1: Rewrite the equation.
Swap the missing number with the number to the right of the equals sign.
So, 46 - ? = 16 should be rewritten as 46 - 16 = ?
Step 2: Solve the new equation. What is 46 - 16?
The image below shows 46 blue dots. 16 are inside a red box.
Count the number of blue dots outside of the red box to solve the equation.
Step 3: Check your work.
When you've found the answer, put it into the original equation: 46 - ? = 16.
If you subtract the correct number from 46, you will get 16!
Solution- 46 - 30 = 16. The missing number is 30.
- Rewrite the equation as 46 - 16 = ?
- Subtract. 46 - 16 = 30.
- Rewrite the equation as 59 - 33 = ?
- Subtract. 59 - 33 = 26.
- Rewrite the equation as 80 - 69 = ?
- Subtract. 80 - 69 = 11.
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Find all of the missing numbers.
HintsStep one: rewrite the equation.
Rewrite the equation so that the missing number is on the right of the equals sign.
In this problem, the missing number is first in the original equation. This is shown by the red box in the image below.
- When the missing number is first, make sure to rewrite your equation with a +.
- The rewritten equation will be 12 + 45 = ?
In this problem, the missing number is second.
- When the missing number is second, do not change the operation sign.
- Swap the numbers as shown in the image. The new equation will be 78 - 15 = ?
Solution? - 45 = 12. The missing number is 57.
- Rewrite the equation as 12 + 45 = ?
- Add 12 + 45 = 57.
- Check your work. Put 57 into the original equation. 57 - 45 = 12
- Rewrite the equation as 43 + 9 = ?
- Add 43 + 9 = 52.
- Check your work. Put 52 into the original equation. 52 - 43 = 9
- Rewrite the equation as 78 - 15 = ?
- Subtract 78 - 15 = 63.
- Check your work. Put 63 into the original equation. 78 - 63 = 15
- Rewrite the equation as 67 + 18 = ?
- Add 67 + 18 = 85.
- Check your work. Put 85 into the original equation. 85 - 67 = 18
-
What's the missing number?
HintsFirst, rewrite the equation so that the missing number is on the right of the = . This is done for you in the image.
Solve the new equation: 51 - 37 = ?
What is 51 - 37?
This image shows 51 blue dots. 37 dots are in the red box.
Count the number of dots outside of the red box to find 51 - 37.
Solution51 - 37 = 14
Put 14 into the original equation to check your work:
51 - 14 = 37.
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Solve the word problem.
HintsWe can write this problem as a subtraction equation.
The number of sweets Razzi started with (70) - the sweets Razzi ate (?) = the number of sweets Razzi has left (49).
Next, rewrite the equation so that the missing number is on the right of the equals sign.
Solve the rewritten equation. The answer tells you how many sweets Razzi ate!
Plug it back into the original equation to check your work.
SolutionRazzi ate 21 sweets.
Step 1: Write the original equation
- The original equation should be written as 70 - ? = 49.
- Rewrite the equation as 70 - 49 = ?
- 70 - 49 = 21.
- Put 21 into the original equation. 70 - 21 = 49
