Year 3 - Maths
Make efficient use of subtraction strategies including column subtraction
Column subtraction
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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 identify the minuend and the subtrahend in column subtraction and explain the column subtraction algorithm. They will subtract from a 2-digit number using column subtraction with exchanging.
Lesson Summary
You will learn to make efficient use of subtraction strategies including column subtraction.
Key Notes
- A mental strategy may be more efficient than a column method
- Look carefully at the numbers in a calculation to decide a method
- Column subtraction might be the most efficient method to use if regrouping is needed
Vocabulary To Learn
- Efficient: Being efficient means finding a way to solve a problem quickly whilst also maintaining accuracy.
- Mental strategy: A mental strategy is a method chosen to find something out which can be done in your head or with some jottings.
- Regrouping: The process of unitising and exchanging between place values is known as regrouping.
Common Mistakes To Avoid
- Pupils may think that column subtraction is always the most efficient strategy where regrouping is needed.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
A mental strategy may be more efficient than a column method. Look carefully at the numbers in a calculation to decide a method.
2. Use this key word in a maths sentence and explain it clearly. 'Efficient'
Being efficient means finding a way to solve a problem quickly whilst also maintaining accuracy. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Pupils may think that column subtraction is always the most efficient strategy where regrouping is needed. Correction: Emphasise calculations where adjustment is the most efficient strategy (e.g. 456 - 199). Regrouping is needed in both the tens and hundreds, but is is not the most efficient strategy.
More Lessons In This Unit
- Identify the minuend and subtrahend in column subtraction Study Guide
- Subtract from a 2-digit number using column subtraction with regrouping Study Guide
- Subtract from a 3-digit number using column subtraction with regrouping Study Guide
- Use column subtraction to subtract from a 2- or 3-digit number Study Guide
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