New
New
Year 3

# Use known facts to add and subtract multiples of 100 within 1000

I can add and subtract multiples of 100

New
New
Year 3

# Use known facts to add and subtract multiples of 100 within 1000

I can add and subtract multiples of 100

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## Lesson details

### Key learning points

1. Known facts can be used to help calculate with multiples of a hundred.
2. If we know that 2 ones plus 4 ones equals 6 ones we know that 2 100s plus 4 100s equals 6 100s.
3. Number facts to 10 can help us to add and subtract multiples of a hundred.

### Common misconception

Pupils may find it difficult to connect calculating with hundreds with known facts.

Pupils need to be encouraged to 'unitise' hundreds to make calculation easier, seeing 500 as 5 lots of one hundred.

### Keywords

• Known facts - A known fact is something that you already know and can use to help you.

• Multiple - A multiple is the result of multiplying a number by another whole number.

Pupils may need base ten blocks ('hundreds') to support their thinking and help them connect calculating with hundreds with known facts (e.g. 3 + 4 = 7 so 300 + 400 = 700). Number lines and bar models are also useful representations for pupils.
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.
What is 40 + 40?
8
16
44
Q2.
100 − 40 =
Q3.
What is the sum of 30, 30 and 10?
60
80
90
Q4.
What is the value of the missing part in the bar model?
Q5.
What is the missing number? + 10 = 120
Correct Answer: 110, one hundred and ten
Q6.
Which pair of numbers do not add up to equal 90?
30 + 60
40 + 50
70 + 20

## Exit quiz

### 6 Questions

Q1.
Which of these numbers are multiples of a hundred?
650
Q2.
Which known fact could you use to help you calculate 500 + 300?
5 + 2 = 7
Correct answer: 3 + 5 = 8
3 + 2 = 5
3 + 3 = 6
Q3.
What is 100 less than 600?
Q4.
Which pairs of numbers are equal to 600?