New
New
Year 2

Use efficient methods to solve subtraction equations

I can use efficient methods to solve subtraction equations.

New
New
Year 2

Use efficient methods to solve subtraction equations

I can use efficient methods to solve subtraction equations.

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Lesson details

Key learning points

  1. Consecutive numbers always have a difference of 1
  2. If the whole and the known part in a subtraction equation are consecutive numbers, the missing part will always be 1
  3. If the known part in a subtraction equation is 1, the whole and the missing part will be consecutive numbers
  4. When the ones digits in the whole and the known part are the same, the missing part will be a multiple of 10

Keywords

  • Consecutive - Numbers which follow each other in order, without gaps.

  • Difference - The result of subtracting one number from another.

  • Whole - All of something; complete.

  • Part - A piece or section of a whole.

Common misconception

When writing equations with consecutive numbers, children may write in the order they are counted , e.g. 56-57 = forwards

Give missing number equations and represent them on part-part-whole models and bar models to consolidate understanding of which numbers in the equation represent the whole and the parts.

For learning cycle 1, ensure representations which draw attention to the linear structure of numbers (e.g. bead strings, Rekenreks, number lines) are used. For learning cycle 2, use representations which highlight the place value of the numbers involved (e.g. Base 10 blocks, images of ten frames).
Teacher tip

Licence

This content is © Oak National Academy Limited (2024), licensed on Open Government Licence version 3.0 except where otherwise stated. See Oak's terms & conditions (Collection 2).

Lesson video

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6 Questions

Q1.
In which of the following equations will you have to bridge 10?
Correct answer: 65 − 26 = ?
38 − 27 = ?
61 − 60 = ?
Q2.
Which of the following equations is correct?
Correct answer: 83 − 26 = 57
45 − 28 = 13
94 − 68 = 34
Q3.
Solve the following equation. 43 − 25 =
Correct Answer: 18
Q4.
Andeep has 76 tickets. He buys the ball. How many tickets does he have left?
An image in a quiz
Correct Answer: 47
Q5.
Andeep had 66 tickets. He bought a plane and now he has 23 tickets left. How much did the plane cost?
An image in a quiz
Correct Answer: 43
Q6.
Match each equation to the correct answer.
Correct Answer:47 − 28 = ___,19

19

Correct Answer:86 − ___ = 34,52

52

Correct Answer:76 − 28 = ___,48

48

6 Questions

Q1.
Write a subtraction equation to calculate the missing part in this bar model and solve it.
An image in a quiz
Correct Answer: 50 − 1 = 49
Q2.
Which of the following equations will have a difference of 1?
83 − 73 = ?
Correct answer: 22 − 21 = ?
38 − 28 = ?
Q3.
One of the missing numbers in this equation is 57 Which of the following could be the other missing number? ___ − ___ = 1
Correct answer: 56
67
Correct answer: 58
Q4.
In which of the following equations will the missing part be a multiple of 10?
Correct answer: 93 − 73 = ?
22 − 21 = ?
38 − 37 = ?
Q5.
Solve the equation. 88 − 58 =
Correct Answer: 30
Q6.
What is the missing digit in the equation?
An image in a quiz
Correct Answer: 2, 2 tens