Year 4 - Maths
Explain the use of placeholders when multiplying whole numbers by 100
Understand what happens when a number is multiplied or divided by 10 and 100
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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 explain the relationship between multiplying and dividing a number by 10 and multiples of 10.
Lesson Summary
You will learn to use place value to explain placing 2 0's after the final digit when we multiply whole numbers by 100.
Key Notes
- Multiples of 100 have zero in the tens and ones column.
- When a number is multiplied by one hundred the product is a multiple of one hundred.
- Multiplying by one hundred moves all the digits two columns to the left making the digits one hundred times the size.
Vocabulary To Learn
- Placeholder: A placeholder is where we use the digit 0 to hold a place in a number and maintain place value.
- Magnitude: The magnitude of a number is its distance from 0
Common Mistakes To Avoid
- Many pupils believe that 'adding 2 zeros' is multiplying by 100 which can lead to difficulties later on when they are introduced to decimal numbers.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
Multiples of 100 have zero in the tens and ones column. When a number is multiplied by one hundred the product is a multiple of one hundred.
2. Use this key word in a maths sentence and explain it clearly. 'Placeholder'
A placeholder is where we use the digit 0 to hold a place in a number and maintain place value. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Many pupils believe that 'adding 2 zeros' is multiplying by 100 which can lead to difficulties later on when they are introduced to decimal numbers. Correction: Don't dismiss it. It's a pattern that has been spotted and generalised. Do encourage the children to work with physical resources that don't involve the numbers themselves so they can understand that it isn't adding zero but changing place value.
More Lessons In This Unit
- Explain how making a factor 10 times the size affects the product Study Guide
- Explain how making a factor 100 times the size affects the product Study Guide
- Explain how making the dividend 10 times the size affects the quotient Study Guide
- Explain how making the dividend 100 times the size affects the quotient Study Guide
- Explain the relationship between multiplying a number by 10 and multiples of 10 Study Guide
- Explain the relationship between multiplying a number by 100 and multiples of 100 Study Guide
- Explain the removal of placeholders when dividing whole numbers by 100 Study Guide
- Scale division facts derived from multiplication facts by 100 Study Guide
- Scale known multiplication facts by 100 Study Guide
- Understand that dividing a number by 10 makes it one-tenth times the size Study Guide
- Understand that multiplying by 10 makes a number ten times the size Study Guide
- Use knowledge of the composition of 100 to multiply and divide by 100 in different ways Study Guide
- Use place value to explain placing a zero after the final digit when we multiply whole numbers by 10 Study Guide
- Use place value to explain removing the zero in the ones from a multiple of ten when we divide by 10 Study Guide
Browse all guides in the Year 4 Maths guide library.