Year 4 - Maths
Decide on the most efficient subtraction strategy, including column subtraction
Review of column addition and 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 revisit column addition with regrouping and column subtraction with exchanging to solve problems.
Lesson Summary
You will learn to make efficient use of subtraction strategies, including column subtraction.
Key Notes
- Look carefully at the numbers in a calculation.
- Column subtraction might be the most efficient method to use if regrouping is needed.
- Use a mental strategy where it would be more efficient.
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.
- Regroup: The process of unitising and exchanging between place values is known as regrouping.
Common Mistakes To Avoid
- When using adjustment (e.g. 456 − 199), pupils may forget whether they have to subtract or add 1 after they have subtracted 200
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
Look carefully at the numbers in a calculation. Column subtraction might be the most efficient method to use if regrouping is needed.
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: When using adjustment (e.g. 456 − 199), pupils may forget whether they have to subtract or add 1 after they have subtracted 200. Correction: Ask pupils if they subtract 200 then subtract 1 more, how much have they subtracted altogether? They should see that they have subtracted 201, not 199 A number line representation will support pupil's understanding with this.
More Lessons In This Unit
- Review adding 2-digit numbers using column addition without regrouping Study Guide
- Review adding 3-digit numbers using column addition without regrouping Study Guide
- Review and use knowledge of place value to correctly lay out column addition Study Guide
- Review column addition and identify the addends and sum Study Guide
- Review identifying the minuend and subtrahend in column subtraction Study Guide
- Review using column addition to add 2- and 3-digit numbers by regrouping ones Study Guide
- Review using column addition to add 2- and 3-digit numbers by regrouping tens Study Guide
- Review using column addition with regrouping in the ones and tens columns Study Guide
- Review using column subtraction to subtract without regrouping Study Guide
- Review using column subtraction with regrouping from hundreds to tens Study Guide
- Review using column subtraction with regrouping from tens to ones Study Guide
- Review using known facts and strategies to accurately and efficiently use and check column addition Study Guide
- Use column addition to solve problems in different contexts Study Guide
- Use knowledge of column addition to solve problems in a range of contexts Study Guide
Browse all guides in the Year 4 Maths guide library.