Inverse Operations

Inverse means the opposite. Inverse operations are useful because they help us to check our answers using number relationships.

Operations

In maths, an operation is what you do to solve a calculation (add, subtract, multiply or divide).
Each operation has an inverse.
Bar models can help us to see number relationships and inverse operations.

Addition and subtraction

If we have 4 and add 3, we get 7.
- 4 + 3 = 7
If we have 7 and subtract 3, we get 4.
- 7 - 3 = 4
So subtracting 3 is the inverse operation of adding 3, as it takes us back to 4.

Multiplication and division

If we have 5 and multiply it by 3, we get 15.
- 3 x 5 = 15
If we have 15 and divide it by 3, we get 5.
- 15 ÷ 3 = 5
So dividing by 3 is the inverse operation of multiplying by 3, as it takes us back to 5.

1Year 3 - Number

2Year 3 - Measurement

2.1Length

2.1.1Length

2.1.2Comparing Lengths

2.1.3Add & Subtract Lengths

2.1.4Perimeter

2.2Mass

2.2.1Mass

2.2.2Comparing Masses

2.2.3Add & Subtract Masses

2.3Volume & Capacity

2.3.1Volume & Capacity

2.3.2Comparing Volumes

2.3.3Add & Subtract Volumes

2.4Money

2.4.1Money

2.4.2Counting Money

2.4.3Adding & Subtracting Money

2.5Time

2.5.1Units of Time

2.5.2Clocks

2.5.3Telling the Time

2.5.4Time of the Day

2.5.512-Hour & 24-Hour Clocks

2.5.6Measuring Time

3Year 3 - Geometry

3.1Angles

3.1.1Angles in Degrees

3.1.2Types of Angle

3.2Properties of Shapes

3.2.12D Shapes

3.2.23D Shapes

3.3Straight Lines

3.3.1Straight Lines

3.3.2Parallel & Perpendicular Lines

4Year 3 - Statistics

4.1Statistics

4.1.1Statistics

4.1.2Pictograms & Bar Charts

5Year 4 - Number

6Year 4 - Measurement

6.1Units

6.1.1Metric Measurements

6.1.2Adding & Subtracting Money

6.2Time

6.2.1Converting Units of Time

6.2.2Changing the 12-Hour Clock to the 24-Hour Clock

6.2.3Changing the 24-hour Clock to the 12-Hour Clock

7Year 4 - Geometry

7.1Properties of Shapes

7.1.1Symmetry

7.1.2Types of Triangle

7.1.3Quadrilaterals

7.2Perimeter & Area

7.2.1Perimeter

7.2.2Area

7.3Position & Direction

7.3.1Coordinates

7.3.2Translation

8Year 4 - Statistics

8.1Statistics

8.1.1Types of Data

8.1.2Pictograms & Bar Charts

8.1.3Line Graphs

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