Year 3 - Maths
Subtract 3-digit multiples of 10 by finding the difference between them
Informal and mental strategies for adding and subtracting two 3-digit numbers
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This pupil-friendly study guide includes a unit summary, clear notes, common mistakes, and quick questions with answers.
Unit Summary
In this unit pupils will add and subtract two 3-digit numbers using partitioning, adjusting, redistribution and bridging.
Lesson Summary
You will learn to subtract 3-digit multiples of 10 by finding the difference between them.
Key Notes
- When numbers are close together, the difference between them is small.
- Finding the difference means we count on from the subtrahend to the minuend.
- A number line or a bar model can represent finding the difference.
Vocabulary To Learn
- Minuend: The minuend is the number being subtracted from.
- Subtrahend: A subtrahend is a number subtracted from another.
- Difference: The difference is the result after subtracting one number from another.
Common Mistakes To Avoid
- Children will often reverse the minuend and subtrahend because they don't always appear in the order that they would in an expression.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
When numbers are close together, the difference between them is small. Finding the difference means we count on from the subtrahend to the minuend.
2. Use this key word in a maths sentence and explain it clearly. 'Minuend'
The minuend is the number being subtracted from. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Children will often reverse the minuend and subtrahend because they don't always appear in the order that they would in an expression. Correction: Give time to ensure that the children understand the bar model representation and encourage them to discuss which number is the minuend and which is the subtrahend before engaging in a strategy for mental subtraction.
More Lessons In This Unit
- Add 2 and 3-digit numbers by redistributing Study Guide
- Add two 3-digit numbers using adjusting strategies Study Guide
- Add two 3-digit numbers using partitioning Study Guide
- Choose the most efficient strategy to add two 3-digit numbers Study Guide
- Choose the most efficient strategy to subtract from a 3-digit number Study Guide
- Subtract 2 or 3-digit numbers using partitioning and bridging a multiple of 10 Study Guide
- Subtract a pair of 2-digit numbers by finding the difference Study Guide
- Use addition and subtraction to solve problems in different contexts Study Guide
- Use addition and subtraction to solve problems involving bar charts, pictograms and tables Study Guide
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