Year 2 - Maths
Solve problems involving subtraction when bridging 10
Addition and subtraction of two 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 apply their knowledge of known facts and understanding of place value to add and subtract with 2-digit numbers both within and across the tens boundary.
Lesson Summary
You will learn to solve problems involving subtraction of two-digit numbers that cross the tens boundary.
Key Notes
- Some problems involving the subtraction of two-digit numbers, can be solved by bridging 10
- We can look to see if the ones digits cross the tens boundary to find out if we must use the bridge 10 strategy
Vocabulary To Learn
- Partition: To split a whole up into parts
- Part: A piece or section of a whole
- Bridge 10: An addition or subtraction strategy where numbers are partitioned to reach the previous or next multiple of 10, so bonds to 10 can be used to calculate more efficiently.
Common Mistakes To Avoid
- When subtracting, children may partition the whole and the part, look at the ones digits involved and simply subtract the smaller digit from the larger digit, e.g. solve 75 - 36 as 70 - 30, then 6 - 1
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
Some problems involving the subtraction of two-digit numbers, can be solved by bridging 10. We can look to see if the ones digits cross the tens boundary to find out if we must use the bridge 10 strategy.
2. Use this key word in a maths sentence and explain it clearly. 'Partition'
To split a whole up into parts. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: When subtracting, children may partition the whole and the part, look at the ones digits involved and simply subtract the smaller digit from the larger digit, e.g. solve 75 - 36 as 70 - 30, then 6 - 1. Correction: Consider whether or not the equation involved will require the 10 tens boundary to be crossed before solving, referring specifically to subtracting the ones digit from the whole number, e.g. think 75-6 rather than 5 -6.
More Lessons In This Unit
- Add 2-digit numbers when crossing the tens boundary Study Guide
- Add two-digit numbers without crossing the tens boundary Study Guide
- Combine tens and ones within equations Study Guide
- Create addition and subtraction problems Study Guide
- Explain different strategies used to subtract Study Guide
- Find the missing addend when adding two-digit numbers Study Guide
- Find the missing part when subtracting two-digit numbers Study Guide
- Solve equations involving the subtraction of two-digit numbers Study Guide
- Solve problems involving addition and subtraction Study Guide
- Solve problems involving subtraction of two-digit numbers Study Guide
- Solve problems involving the addition of two-digit numbers Study Guide
- Subtract two-digit numbers crossing the tens boundary Study Guide
- Use efficient addition strategies to calculate Study Guide
- Use efficient methods to solve subtraction equations Study Guide
Browse all guides in the Year 2 Maths guide library.