New
New
Year 3

# Make efficient use of subtraction strategies including column subtraction

I can make efficient use of subtraction strategies including column subtraction.

New
New
Year 3

# Make efficient use of subtraction strategies including column subtraction

I can make efficient use of subtraction strategies including column subtraction.

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## Lesson details

### Key learning points

1. A mental strategy may be more efficient than a column method
2. Look carefully at the numbers in a calculation to decide a method
3. Column subtraction might be the most efficient method to use if regrouping is needed

### Common misconception

Pupils may think that column subtraction is always the most efficient strategy where regrouping is needed.

Emphasise calculations where adjustment is the most efficient strategy (e.g. 456 - 199). Regrouping is needed in both the tens and hundreds, but is is not the most efficient strategy.

### Keywords

• Efficient - Being efficient means finding a way to solve a problem quickly whilst also maintaining accuracy.

• Mental strategy - A mental strategy is a method chosen to find something out which can be done in your head or with some jottings.

• Regrouping - The process of unitising and exchanging between place values is known as regrouping.

### 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.
Where is regrouping needed in the column subtraction?
In the ones
In the ones and tens
Regrouping is not needed
Q2.
Where is regrouping needed in the column subtraction?
In the ones
In the tens
Correct answer: In the ones and tens
Regrouping is not needed
Q3.
Finish the column subtraction. What is the difference?
Correct Answer: 216, two hundred and sixteen
Q4.
How would you subtract 99 from 387?
Subtract 100 then subtract 1 more
Subtract 100 then subtract 9 more
Q5.
Calculate 387 − 99 =
Correct Answer: 288, two hundred and eighty-eight
Q6.
Complete the column subtraction. What is the difference?
Correct Answer: 317, three hundred and seventeen

## Exit quiz

### 6 Questions

Q1.
Which calculations would it be most efficient to answer using a mental strategy?
763 − 481
742 − 337
Q2.
Which calculations would it be most efficient to answer using column subtraction?
751 − 749
845 − 199
Q3.
Sam calculates 401− 396 by counting on from 396 He found a difference of .
Q4.
Aisha wants to calculate 827 − 299 How should she calculate this using a mental strategy?
Subtract 300 then subtract 1 more