Year 2 - Maths
Use number facts to add or subtract a one-digit number and a two-digit number.
Adding and subtracting ones and tens to and from 2-digit numbers
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Study Guides
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 add and subtract a single digit number and a two-digit number.
Key Notes
- Known facts can be used to help solve equations with larger numbers.
- Partitioning a two-digit number into tens and ones can help with seeing the pattern in the ones.
- When adding to or subtracting from the ones without crossing the tens boundary, the tens digit does not change.
Vocabulary To Learn
- Equation: An equation has an equal sign. It shows that what is on the left of the equation is equal to what is on the right.
Common Mistakes To Avoid
- Children may not recognise known facts when addends are presented in different order, e.g. they may not use 7+1 to solve 61 +7 They may also confuse tens and ones digits.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
Known facts can be used to help solve equations with larger numbers. Partitioning a two-digit number into tens and ones can help with seeing the pattern in the ones.
2. Use this key word in a maths sentence and explain it clearly. 'Equation'
An equation has an equal sign. It shows that what is on the left of the equation is equal to what is on the right. 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 not recognise known facts when addends are presented in different order, e.g. they may not use 7+1 to solve 61 +7 They may also confuse tens and ones digits. Correction: Focus on efficient ways of working and, when working in the abstract, partition the two-digit number into tens and ones, so the tens and ones digits can be easily identified and the commutative aspect of the ones digit can be more easily seen.
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 by bridging a multiple of ten 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 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.