# Solve problems involving addition and subtraction

I can solve problems involving the addition and subtraction of two-digit numbers.

# Solve problems involving addition and subtraction

I can solve problems involving the addition and subtraction of two-digit numbers.

## Lesson details

### Key learning points

- When solving problems, it must be decided whether to add or subtract in order to solve it.
- If the ones digits crosses the tens boundary, it shows that the bridge 10 strategy can be used.
- A number line can be drawn or visualised to help solve problems efficiently.

### Common misconception

When solving problems involving equations with more than two parts, children may automatically consider the numbers in the order given instead of considering the order they would find easier.

Encourage children to solve equations in different orders, comparing which they find easiest and articulating their thinking as they calculate.

### Keywords

Addition - Addition involves finding the total, or sum, by combining two or more numbers.

Subtraction - Subtraction involves taking one number away from another.

Bridge 10 - An addition or subtraction strategy where numbers are partitioned to reach the previous or next multiple of 10, so bonds to 10 can be used to calculate more efficiently.

### 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

20 + 19 + 34 = ?

30 + 13 + 23 = ?

20 + 15 + 42 = ?