Year 3 - Maths
Solve problems by adding and subtracting to or from 3-digit numbers
Representing 3-digit numbers, comparing and positioning on number lines
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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 knowledge of place value to represent a 3-digit number in different ways. They will compare and order 3-digit numbers and position on number lines and unmarked number lines.
Lesson Summary
You will learn to solve problems by adding to and subtracting from 3-digit numbers.
Key Notes
- Number lines can record the steps in our thinking when we are partitioning to add and subtract.
- The 1s digit does not change when you add or subtract a multiple of ten.
- Number facts to 10 help when crossing the 10s and 100s boundaries.
Vocabulary To Learn
- bridge: Bridging is a strategy which uses addition or subtraction to cross a number boundary.
- partition: Partition means splitting an object or value down into smaller parts.
- 100s boundary: The 100s boundary is the point at which the numbers change into 100s numbers, or from one set of hundreds to another.
Common Mistakes To Avoid
- Pupils may struggle to partition 10s numbers to help them bridge a 100s boundary.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
Number lines can record the steps in our thinking when we are partitioning to add and subtract. The 1s digit does not change when you add or subtract a multiple of ten.
2. Use this key word in a maths sentence and explain it clearly. 'bridge'
Bridging is a strategy which uses addition or subtraction to cross a number boundary. 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 struggle to partition 10s numbers to help them bridge a 100s boundary. Correction: Encourage pupils to calculate the number of tens needed to add or subtract to the 100s number, then add or subtract the remainder.
More Lessons In This Unit
- Add and subtract to and from a 3-digit number bridging 100 Study Guide
- Comparing and ordering numbers with 1, 2 and 3 digits Study Guide
- Count forwards and backwards in multiples of 2, 20, 5, 50 and 25 Study Guide
- Count forwards and backwards within 3-digits Study Guide
- Estimate the position of 3-digit numbers on unmarked number lines Study Guide
- Ordering sets of 3-digit numbers Study Guide
- Partition 3-digit numbers in different ways Study Guide
- Position 3-digit numbers on number lines Study Guide
- Represent a 3-digit number up to 1,000 in different ways Study Guide
- Solve problems by counting forwards and backwards in multiples of 2, 20, 5, 50 and 25 Study Guide
- Use known facts to add and subtract multiples of 100 within 1000 Study Guide
- Use known facts to add and subtract to and from multiples of 100 Study Guide
- Use known facts to solve problems involving partitioning numbers Study Guide
- Write a 3-digit multiple of 10 as a multiplication equation Study Guide
Browse all guides in the Year 3 Maths guide library.