Subtraction (Counting on) — Let's Practise!
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Basics on the topic Subtraction (Counting on) — Let's Practise!
Using Addition to Subtract – Introduction
Get ready because today we're going to practise subtraction - counting on. It’s a helpful way to understand subtraction better by using addition. Ready to begin? Let's go!
What Does it Mean to Subtract by Counting On?
Subtraction by counting on means using mental maths and turning a subtraction problem into an addition problem to make it easier to solve.
For example, if you have the subtraction problem 35 - 15, you can flip it to create an addition problem: 15 + ? = 35. You can then count on from 15 to get to 35. This method can help you find the missing number more easily. Let’s practise this with some problems!
Subtraction by Counting On – Example
Let's solve a subtraction problem by counting on:
Problem
If Alex has 35 nails but only needs 15, how many will he have left?
Solution
Follow these simple steps to find the solution.
| Step | Explanation | Result |
|---|---|---|
| Create the subtraction equation | 35 - 15 | |
| Flip to create the addition equation | 15 + ? = 35 | |
| Solve by counting on | 15 + 20 = 35 | 20 |
So, 35 minus 15 equals 20! Alex will have 20 nails left.
Using Addition to Subtract – Guided Practice
Let's try another problem together.
Problem
If Imani has 47 screws but only uses 23, how many are left?
So, 47 minus 23 equals 24! Imani will have 24 screws left.
Subtraction by Counting On – Application
Now, try solving this problem on your own:
Problem If Mia has 96 nuts, but 34 get eaten, how many are left?
So, 96 minus 34 equals 62! Mia will have 62 nuts left.
Subtraction by Counting On – Examples
To help yourself in becoming fluent in subtraction by counting on, have a look at some more examples and complete them by following the steps.
| Problem | Subtraction Equation | Addition Equation | Solution |
|---|---|---|---|
| 35 - 15 | 35 - 15 | 15 + ? = 35 | 20 |
| 47 - 23 | 47 - 23 | 23 + ? = 47 | 24 |
| 96 - 34 | 96 - 34 | 34 + ? = 96 | 62 |
| 82 - 34 | 82 - 34 | 34 + ? = 82 | 48 |
Subtraction by Counting On – Summary
Key Learnings from this Text:
- Subtracting by counting on helps us understand subtraction by turning it into an addition problem.
- It is a helpful method to subtract without using a calculator or a written method.
- Create a subtraction equation and then flip it to create an addition equation.
- Solve the addition equation by counting on to find the missing number.
Keep practising using addition to subtract to become a maths whiz! Check out more fun maths problems and activities on our website, such as subtraction by adjusting numbers, using place value to subtract or using number lines to subtract.
Subtraction by Counting On – Frequently Asked Questions
Subtraction (Counting on) — Let's Practise! exercise
-
How would we solve this problem using counting on?
HintsThe first step is to find the subtraction equation you are trying to solve.
You can then turn the subtraction equation into an addition equation.
Count on to find the answer before filling it in.
Solution- Start with a subtraction equation: 28 - 14 = __
- Flip it to make an addition equation: 14 + __ = 28
- Count on to find the answer.
- Fill in the correct answer: 14 + 14 = 28
-
How many bolts will Mr. Squeaks have left?
HintsWhat is the subtraction equation you are trying to solve?
The subtraction equation is 46 - 33 = ?
How can this be made into an addition equation?
We can change this to 33 + __ = 46
Count on from 33 to reach 46.
SolutionThe subtraction equation being solved is 46 - 33 = ?
We can flip this to 33 + __ = 46.
Count on from 33 to 46.
33 + 13 = 46
46 - 33 = 13
-
Can you solve these subtraction problems?
HintsCount on from the smaller number to the larger number.
Double check your answers by subtracting the smaller number from the larger number.
Solution1.) 24 - 11 = ?
11 + 13 = 24
24 - 11 = 13
2.) 54 - 37 = ?
37 + 17 = 54
54 - 37 = 17
3.) 68 - 35 = ?
35 + 33 = 68
68 - 35 = 33
-
What is the missing number?
HintsIf you are solving an addition equation, count on from the smaller number to the larger number.
If you are solving a subtraction equation, you can flip it into an addition equation and then count on to solve.
Perform the inverse, or opposite, operation to check your answers.
Solution27
- 61 - 34 = 27
- 29 + 27 = 56
- 84 - 57 = 27
- 60 - 29 = 31
- 84 - 53 = 31
- 25 + 31 = 56
- 94 - 51 = 43
- 61 - 18 = 43
- 32 + 43 = 75
-
How many pieces of cheese are left?
HintsThe subtraction equation we are trying to solve is 20 - 9 = ?
We can flip this to 9 + __ = 20.
Count on from 9 to 20.
Use this number line to help you.
SolutionMr. Squeaks has 11 pieces of cheese left.
20 - 9 = ?
9 + __ = 20
9 + 11 = 20
20 - 9 = 11
-
Can you solve the problems?
HintsWork out what the subtraction equation is for each problem.
Flip it to an addition equation and count on to solve.
For the first question, the subtraction equation is 60 - 11 = ?
We can flip this to 11 + __ = 60.
Solution- Sally started counting down to her birthday when there were 60 days to go. Now there are only 11 days to go. 49 days have passed.
- The bakery made 98 cheese straws in the morning and sold 76. They have 22 cheese straws left.
- Dave has to wash 113 windows in a day. He has done 84 so far and has 29 left to go.
Subtract by Adding
Subtraction (Counting on) — Let's Practise!
Using Base 10 Blocks to Subtract 2 Digit Numbers
Subtraction - Adjusting Numbers
Using Place Value to Subtract Two Digit Numbers (No Regrouping)
Using Place Value to Subtract Two Digit Numbers (No Regrouping)—Let's Practise
Using Base Ten Blocks to Subtract Two Digit Numbers (With regrouping)
Using Place Value to Subtract (Regrouping)
