# Add and subtract to and from a 3-digit number bridging 100

I can add and subtract to and from a 3-digit number bridging 100.

# Add and subtract to and from a 3-digit number bridging 100

I can add and subtract to and from a 3-digit number bridging 100.

## Slide deck

## Lesson details

### Key learning points

- Addition and subtraction calculations can represent counting on and back over the 100s boundary.
- When you count on in tens, sometimes the 10s digit only changes and sometimes the 100s digit changes.
- When you count back in tens, sometimes the 10s digit only changes and sometimes the 100s digit changes.

### Common misconception

Pupils may partition numbers incorrectly when adding or subtracting across a 100s boundary.

Encourage pupils to add or subtract to first the 100s number, using number pairs that total 10 or 100.

### Keywords

Bridging - A mental strategy which uses addition or subtraction to cross a number boundary.

Partition - Splitting an object or value down into smaller parts.

100s boundary - The point at which numbers change into 100s numbers, or from one set of hundreds to another.

### 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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