Missing Numbers in Subtraction—Let's Practise!
Basics on the topic Missing Numbers in Subtraction—Let's Practise!
Join Razzi and learn how to find missing numbers in subtraction problems.
Missing Numbers in Subtraction—Let's Practise! exercise

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.

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.

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.

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.

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