Make efficient use of subtraction strategies including column subtraction | Maths

Starter quiz

Where is regrouping needed in the column subtraction?

In the ones

In the tens ✓

In the ones and tens

Regrouping is not needed
Where is regrouping needed in the column subtraction?

In the ones

In the tens

In the ones and tens ✓

Regrouping is not needed
Finish the column subtraction. What is the difference?

'216' ✓
How would you subtract 99 from 387?

Subtract 100 then subtract 1 more

Subtract 100 then add 1 ✓

Subtract 100 then subtract 9 more

Subtract 100 then add 9
Calculate 387 − 99 = ______

'288' ✓
Complete the column subtraction. What is the difference?

'317' ✓

Exit quiz

Which calculations would it be most efficient to answer using a mental strategy?

302 − 297 ✓

763 − 481

783 − 200 ✓

742 − 337
Which calculations would it be most efficient to answer using column subtraction?

941 − 323 ✓

751 − 749

845 − 199

835 − 567 ✓
Sam calculates 401− 396 by counting on from 396 He found a difference of ______.

'5' ✓
Aisha wants to calculate 827 − 299 How should she calculate this using a mental strategy?

Subtract 300 then subtract 1 more

Subtract 300 then add 1 ✓

Subtract 200 then subtract 1 more

Subtract 200 then add 1
What is 555 − 199 = ______?

'356' ✓
Calculate 941 − 323 = ______

'618' ✓

Worksheet

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Lesson Details

Key learning points

A mental strategy may be more efficient than a column method
Look carefully at the numbers in a calculation to decide a method
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.