# Find 10 more or less than a 2-digit number.

I can find 10 more or 10 less than a two-digit number.

# Find 10 more or less than a 2-digit number.

I can find 10 more or 10 less than a two-digit number.

## Lesson details

### Key learning points

- When finding 10 more or 10 less than any two-digit number, the ones digits does not change.
- When finding 10 more than a number below 100, the tens digit increases by one.
- When finding 10 less than a number below 100, the tens digit decreases by one.

### Common misconception

Children may default to counting in ones to find ten more or ten less.

Use representations that highlight the structure of the base 10 system, e.g. Base 10 blocks/one hundred squares, and also 'dual counting' to support understanding of 'unitising', i.e. that using 'ten' as a unit can help to calculate more efficiently.

### Keywords

10 more - 10 more than is when there is a greater amount by 10 than another item in the set.

10 less - 10 less than is when there is a smaller value by 10

Increase - Make something bigger (in size or quantity).

Decrease - Make something smaller (in size or quantity).

### 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).

## Video

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## Starter quiz

### 6 Questions

## Exit quiz

### 6 Questions

40

20

90

50

100

40

50

100

60

the tens digit increases by one, but the ones digit remains the same.

the tens digit decreases by one, but the ones digit remains the same.

27

33

56

75