Year 5 - Maths
Multiply a 2-digit number by a 1-digit number using expanded multiplication (regrouping 10s to 100s)
Multiplication by partitioning leading to short multiplication (2 by 1-digit)
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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 multiply a 2-digit number by a single-digit number using partitioning and representations using expanded multiplication and using short multiplication.
Lesson Summary
You will learn to use expanded multiplication to record regrouping from the 10s to the 100s.
Key Notes
- If the product of the single digit and the tens number is greater than 100 then you regroup ten tens into one hundred.
- If the product of the single digit and the tens number is greater than 100 the partial product will be a 3-digit number.
- There are similarities between the representations of multiplication.
Vocabulary To Learn
- expanded multiplication: Expanded multiplication is a way of recording the steps focusing on partitioning one or more factors and showing partial products.
- regroup: The process of unitising and exchanging between place values is known as regrouping.
Common Mistakes To Avoid
- Pupils may not align or regroup correctly leading to an inaccurate calculation.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
If the product of the single digit and the tens number is greater than 100 then you regroup ten tens into one hundred. If the product of the single digit and the tens number is greater than 100 the partial product will be a 3-digit number.
2. Use this key word in a maths sentence and explain it clearly. 'expanded multiplication'
Expanded multiplication is a way of recording the steps focusing on partitioning one or more factors and showing partial products. 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 not align or regroup correctly leading to an inaccurate calculation. Correction: Model accurately what happens when we regroup from 10s to 100s. Why did this happen? How do we record this?
More Lessons In This Unit
- Estimate and multiply a 2-digit by a 1-digit number using expanded and short multiplication Study Guide
- Multiply a 2-digit number by a 1-digit number using expanded multiplication (no regroups) Study Guide
- Multiply a 2-digit number by a 1-digit number using expanded multiplication (regrouping 1s to 10s) Study Guide
- Multiply a 2-digit number by a 1-digit number using partitioning Study Guide
- Multiply a 2-digit number by a 1-digit number using partitioning and representations (one regroup) Study Guide
- Multiply a 2-digit number by a 1-digit number using partitioning and representations (two regroups) Study Guide
- Multiply a 2-digit number by a 1-digit number using short multiplication (no regroups) Study Guide
- Multiply a 2-digit number by a 1-digit number using short multiplication (regrouping 10s to 100s) Study Guide
- Multiply a 2-digit number by a 1-digit number using short multiplication (regrouping 1s to 10s) Study Guide
Browse all guides in the Year 5 Maths guide library.