5.3.2
Addition & Subtraction
Addition in your Head
Addition in your Head
You can use knowledge of place value and number bonds to help us add.


67 + 91
67 + 91
- When trying to work out 67 + 91, you need to use your number bonds.
- You know that 7 + 1 = 8.
- So your 'ones' must be 8.


'Tens'
'Tens'
- You know that 9 + 6 = 15.
- So your 'tens' must be 15.
- 15 'tens' is the same as 5 'tens' and 1 'hundred'.


And the answer is...
And the answer is...
- So there are:
- 8 'ones'.
- 5 'tens'.
- 1 'hundred'.
- The answer is to 67 + 91 is 158.


98 + 15
98 + 15
- This is the same even if there is carrying to do!
- You know that 8 + 5 = 13.
- So your 'ones' must be 13.
- You will need to carry the 1 into the 'tens' column.


The 'tens'
The 'tens'
- You know that 9 + 1 = 10.
- You need to add 1 more from the 1 you carried from the 'ones'.
- So your 'tens' must be 11.
- 11 'tens' is the same as 1 'ten' and 1 'hundred'.


And the answer is...
And the answer is...
- So there are:
- 3 'ones'.
- 1 'ten'.
- 1 'hundred'.
- The answer is to 98 + 15 is 113.
Subtraction in your Head
Subtraction in your Head
You can use knowledge of place value and number bonds to help us subtract.


67 − 23
67 − 23
- When trying to work out 67 − 23, you need to use your number bonds.
- You know that 7 − 3 = 4.
- So your 'ones' must be 4.


'Tens'
'Tens'
- You know that 6 − 2 = 4.
- So your 'tens' must be 4.


And the answer is...
And the answer is...
- So there are:
- 4 'ones'.
- 4 'tens'.
- The answer is to 67 − 23 is 44.


73 − 18
73 − 18
- This is the same even if there is borrowing (exchanging) to do!
- You can use number bonds to help you when you need to borrow (exchange) in a subtraction.
- You know that 3 + 5 + 10 = 18.
- So 73 − 3 − 5 − 10 = 73 − 18.


And the answer is...
And the answer is...
- 73 − 3 − 5 − 10 = 55.
1Year 5 - Number
1.1Number & Place Value
1.2Addition & Subtraction
1.3Multiplication & Division
2Year 5 - Measurement
2.2Perimeter & Area
2.3Time
3Year 5 - Geometry
3.1Properties of 3D Shapes
3.2Properties of 2D Shapes
3.4Position & Direction
4Year 5 - Statistics
5Year 6 - Number
5.1Number & Place Value
5.2Multiplication & Division
5.3Mental Maths
5.4Order of Operations
5.5Problem Solving
5.6Fractions & Decimals
6Year 6 - Ratio & Proportion
6.2Percentages
6.3Scale
7Year 6 - Algebra
7.2Missing Number Problems
8Year 6 - Measurement
8.1Problem Solving
8.2Unit Conversion
8.3Perimeter, Area & Volume
8.4Angles
8.5Circles
8.6Coordinate Grids
9Year 6 - Statistics
9.1Displaying Data
9.2Averages
Jump to other topics
1Year 5 - Number
1.1Number & Place Value
1.2Addition & Subtraction
1.3Multiplication & Division
2Year 5 - Measurement
2.2Perimeter & Area
2.3Time
3Year 5 - Geometry
3.1Properties of 3D Shapes
3.2Properties of 2D Shapes
3.4Position & Direction
4Year 5 - Statistics
5Year 6 - Number
5.1Number & Place Value
5.2Multiplication & Division
5.3Mental Maths
5.4Order of Operations
5.5Problem Solving
5.6Fractions & Decimals
6Year 6 - Ratio & Proportion
6.2Percentages
6.3Scale
7Year 6 - Algebra
7.2Missing Number Problems
8Year 6 - Measurement
8.1Problem Solving
8.2Unit Conversion
8.3Perimeter, Area & Volume
8.4Angles
8.5Circles
8.6Coordinate Grids
9Year 6 - Statistics
9.1Displaying Data
9.2Averages
Unlock your full potential with Seneca Premium
Unlimited access to 10,000+ open-ended exam questions
Mini-mock exams based on your study history
Unlock 800+ premium courses & e-books