Year 2 - Maths
Subtract by bridging a multiple of ten
Adding and subtracting ones and tens to and from 2-digit numbers
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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 add and subtract 1s and 10s from 2 digit numbers. They will use number facts to add/subtract a single-digit number to/from a 2-digit number. They will use a part-part-whole model to represent addition and subtraction.
Lesson Summary
You will learn to bridge ten to subtract single digit numbers from two-digit numbers.
Key Notes
- When we subtract a one-digit from a two-digit number, the equation may be solved more efficiently by 'bridging ten'.
- When bridging a multiple of ten, the number that is subtracted is partitioned to reach the previous multiple of ten.
- Bridging ten is an efficient strategy because number pairs to ten can be used to calculate more easily.
Vocabulary To Learn
- Bridge: A strategy that involves using a multiple of ten as a 'bridge' so numbers can be partitioned to make use of bonds to ten and calculate efficiently.
- Partition: To split a whole up into parts.
Common Mistakes To Avoid
- Children may think the multiple of ten before 43 is 30, or partition the subtrahend incorrectly when bridging, meaning they do not use the most efficient strategy.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
When we subtract a one-digit from a two-digit number, the equation may be solved more efficiently by 'bridging ten'. When bridging a multiple of ten, the number that is subtracted is partitioned to reach the previous multiple of ten.
2. Use this key word in a maths sentence and explain it clearly. 'Bridge'
A strategy that involves using a multiple of ten as a 'bridge' so numbers can be partitioned to make use of bonds to ten and calculate efficiently. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: Children may think the multiple of ten before 43 is 30, or partition the subtrahend incorrectly when bridging, meaning they do not use the most efficient strategy. Correction: Display and use the stem sentences to support articulation of how to find the previous multiple of ten. Use ten frames, number lines and one hundred squares to support with appropriate partitioning of numbers.
More Lessons In This Unit
- Add and subtract 1 to and from a 2-digit number crossing the tens boundary Study Guide
- Add and subtract 10 to and from a 2-digit number. Study Guide
- Add and subtract one to or from a two-digit number within a decade Study Guide
- Add by bridging a multiple of ten Study Guide
- Add multiples of 10 to 2-digit numbers. Study Guide
- Find 10 more or less than a 2-digit number. Study Guide
- Partition 2-digit numbers in different ways Study Guide
- Subtract multiples of ten from 2-digit numbers Study Guide
- Use bridging to solve addition and subtraction problems Study Guide
- Use efficient strategies to solve problems Study Guide
- Use number bonds to 10 to add/subtract one-digit and two-digit numbers Study Guide
- Use number facts to add or subtract a one-digit number and a two-digit number. Study Guide
- Use number facts to solve addition and subtraction problems. Study Guide
- Use number facts to solve problems in measures and data contexts Study Guide
Browse all guides in the Year 2 Maths guide library.