# Applying a range of strategies to mentally calculate subtraction

## Lesson details

### Key learning points

1. In this lesson, we will use different mental strategies to calculate subtraction such as partitioning, counting on and using known facts.

### Licence

This content is made available by Oak National Academy Limited and its partners and licensed under Oak’s terms & conditions (Collection 1), except where otherwise stated.

## Video

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## Worksheet

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## Starter quiz

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### 4 Questions

Q1.
What does the word 'efficient' mean?
To do something slowly.
Correct answer: To do something well without wasting energy.
Q2.
Which of these is not a strategy for adding efficiently?
Changing the order of the addends to make a calculation easier
Using doubling and halving
Q3.
When adding 66 and 67 which is an efficient strategy?
Counting on in my head from the largest number
Drawing out a number line
Q4.
When adding 69 and 81 which would be an efficient strategy?
Doubling and halving
Drawing out a number line
Using dienes

## Exit quiz

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### 4 Questions

Q1.
What does the word 'efficient' mean?
To do something slowly.
Correct answer: To do something well without wasting energy.
Q2.
Which of these is not a strategy for subtracting efficiently?
Correct answer: Changing the order of the addends to make a calculation easier
Finding the difference
Partitioning and subtracting one part
Using known facts
Q3.
When calculating 50 - 48 which is an efficient strategy?
Correct answer: Count on to find the difference
Counting back on my fingers
Drawing out a number line
Partitioning and subtracting
Q4.
When calculating 92 - 57 which would be an efficient strategy?
Counting back on my fingers
Drawing out a number line
Correct answer: Partitioning and subtracting one part