Year 3 - Maths
Bridge 100 by subtracting in multiples of 10
Securing place value to 100 and applying to 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 use known facts to find multiples of ten that compose 100 and use known facts to find complements to 100. They will add and subtract multiples of ten, bridging 100.
Lesson Summary
You will learn to use number facts to 20 to subtract multiples of 10 and bridge 100.
Key Notes
- The language of unitising helps us to use number facts to 20 to subtract multiples of 10 crossing the hundreds.
- If 14 subtract 6 is equal to 8 then 14 tens subtract 6 tens is equal to 8 tens or 80.
- Partitioning the subtrahend helps us to cross the 100s boundary.
Vocabulary To Learn
- Subtrahend: The number that is to be subtracted. The second number in a subtraction.
- Minuend: The first number in a subtraction. The number from which another number is to be subtracted.
Common Mistakes To Avoid
- Lack of fluency with number facts to 20 can hinder progress in applying them to multiples of ten.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
The language of unitising helps us to use number facts to 20 to subtract multiples of 10 crossing the hundreds. If 14 subtract 6 is equal to 8 then 14 tens subtract 6 tens is equal to 8 tens or 80.
2. Use this key word in a maths sentence and explain it clearly. 'Subtrahend'
The number that is to be subtracted. The second number in a subtraction. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Lack of fluency with number facts to 20 can hinder progress in applying them to multiples of ten. Correction: Ensure that fluency with number facts to 20 and related subtraction facts is secure or supported so that pupils can apply them.
More Lessons In This Unit
- Bridge 100 by adding in multiples of 10 Study Guide
- Composition of 100 in 10s and 1s Study Guide
- Composition of 100 in 50s, 25s and 20s Study Guide
- Multiples of 10 that total 100 Study Guide
- Represent 3-digit multiples of 10 in different ways Study Guide
- Solve problems using knowledge of addition and subtraction of multiples of 10 Study Guide
- Use known facts to find complements to 100 efficiently Study Guide
- Use known facts to find pairs of numbers that total 100 Study Guide
- Use place value knowledge to write addition and subtraction equations Study Guide
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