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).

Video

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6 Questions

Q1.
Where is regrouping needed in the column subtraction?
An image in a quiz
In the ones
Correct answer: In the tens
In the ones and tens
Regrouping is not needed
Q2.
Where is regrouping needed in the column subtraction?
An image in a quiz
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?
An image in a quiz
Correct Answer: 216, two hundred and sixteen
Q4.
How would you subtract 99 from 387?
Subtract 100 then subtract 1 more
Correct answer: Subtract 100 then add 1
Subtract 100 then subtract 9 more
Subtract 100 then add 9
Q5.
Calculate 387 − 99 =
Correct Answer: 288, two hundred and eighty-eight
Q6.
Complete the column subtraction. What is the difference?
An image in a quiz
Correct Answer: 317, three hundred and seventeen

6 Questions

Q1.
Which calculations would it be most efficient to answer using a mental strategy?
Correct answer: 302 − 297
763 − 481
Correct answer: 783 − 200
742 − 337
Q2.
Which calculations would it be most efficient to answer using column subtraction?
Correct answer: 941 − 323
751 − 749
845 − 199
Correct answer: 835 − 567
Q3.
Sam calculates 401− 396 by counting on from 396 He found a difference of .
An image in a quiz
Correct Answer: 5, five
Q4.
Aisha wants to calculate 827 − 299 How should she calculate this using a mental strategy?
Subtract 300 then subtract 1 more
Correct answer: Subtract 300 then add 1
Subtract 200 then subtract 1 more
Subtract 200 then add 1
Q5.
What is 555 − 199 = ?
Correct Answer: 356, three hundred and fifty-six
Q6.
Calculate 941 − 323 =
Correct Answer: 618, six hundred and eighteen

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