New
New
Year 3

# Solve multi-step addition and subtraction problems efficiently

I can solve multi-step addition and subtraction problems efficiently.

New
New
Year 3

# Solve multi-step addition and subtraction problems efficiently

I can solve multi-step addition and subtraction problems efficiently.

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## Lesson details

### Key learning points

1. Addition and subtraction can be done in any order
2. If you do the addition and subtraction in a different order, the answer will be the same
3. The most efficient order can be chosen by looking at the numbers

### Common misconception

Pupils may struggle when reordering equations where the addends and subtrahends are calculated first (e.g. 455 + 39 - 38)

Give pupils opportunities to explore the relationship between the addend and subtrahend. They could calculate the answers to problems where the subtrahend is one less than the addend (e.g. 45 + 10 - 9). Can they see a pattern in their answers?

### Keywords

• Efficient - Working efficiently means finding a way to solve a problem quickly whilst also maintaining accuracy.

• Reorder - Reorder means arrange something in a different way.

Manipulatives such as tens frames or base ten blocks may be useful for this lesson, although they are most appropriate for cycle 1. Pupils will need some familiarity with rearranging addition and subtraction equations.
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).

## Starter quiz

### 6 Questions

Q1.
Which expression would give the same answer as 12 + 3 − 5?
10 − 5 + 3
Correct answer: 12 − 5 + 3
12 − 3 + 5
Q2.
True or false? 16 + 4 – 2 is equal to 16 – 4 + 2
true
Q3.
Match the expressions with those that have the same answer.
Correct Answer:10 + 6 − 4,10 − 4 + 6

10 − 4 + 6

Correct Answer:10 + 4 − 6,10 − 6 + 4

10 − 6 + 4

Correct Answer:10 + 6 − 5,10 − 5 + 6

10 − 5 + 6

Q4.
What is 16 + 7 + 4 =
Q5.
There are 11 people on a bus. At the next stop, 4 people get on the bus and 2 people get off. How many people are on the bus? Which calculations would give the correct answer?
Correct answer: 11 − 2 + 4 =
11 + 2 − 4 =
Correct answer: 11 + 4 − 2 =
11 − 4 + 2 =
Q6.
What is the missing number? 15 + 5 − \$\$\square\$\$ = 10

## Exit quiz

### 6 Questions

Q1.
Which expression would give the same answer as 15 + 4 − 5?
15 − 4 + 5
5 − 5 + 4
Correct answer: 15 − 5 + 4
Q2.
What is the most efficient order to answer 16 − 6 + 7?
Correct answer: 16 − 6 + 7
16 + 7 − 6
16 + 6 − 7
Q3.
What is 17 − 8 + 3?
13
14
22
Q4.
What is 106 + 25 − 6 =
Correct Answer: 125, one hundred and twenty-five
Q5.
What is 99 + 19 − 18?