Year 2 - Maths
Find the missing addend when adding two-digit numbers
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 find the missing addends when adding two-digit numbers.
Key Notes
- Two-digit numbers can be partitioned to help find a missing digit or a missing addend.
- One equation can be used to help solve another equation.
- The patterns in equations can be used to help find a missing addend.
Vocabulary To Learn
- Addend: Any of the numbers that are added together.
- Digit: A single symbol used to make a numeral.
Common Mistakes To Avoid
- When finding a missing ones digit in an addend, children may confuse the tens and ones digits in the sum, thus adding to the ones to make the amount of the tens digit or vice versa.
3 Quick Questions (With Answers)
1. Solve this in steps: explain the method from this lesson and why each step matters.
Two-digit numbers can be partitioned to help find a missing digit or a missing addend. One equation can be used to help solve another equation.
2. Use this key word in a maths sentence and explain it clearly. 'Addend'
Any of the numbers that are added together. Use this word when showing your method, then check your final answer is reasonable.
3. Spot and fix this common maths mistake.
Mistake: When finding a missing ones digit in an addend, children may confuse the tens and ones digits in the sum, thus adding to the ones to make the amount of the tens digit or vice versa. Correction: Partition the addends into tens and ones so the place value of the digit that is missing is clear.
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 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 subtraction when bridging 10 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.