Subtract from a 3-digit number using column subtraction with regrouping | Maths

Starter quiz

A ten has been regrouped into 10 ones. What number is represented by the base ten blocks?

'51' ✓
In which of these calculations would you need to regroup?
Calculate the difference.

54

56 ✓

64

70
What is the missing subtrahend?

'6' ✓
Calculate the difference.

12

18 ✓

22

92
What is the missing subtrahend?

'13' ✓

Exit 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?

'308' ✓
Finish the column subtraction. What is the difference?

'238' ✓
What is the difference?

257

267 ✓

357

333
What is the difference?

'249' ✓

Worksheet

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Presentation

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Video

Lesson Details

Key learning points

Start with the numbers with the smallest place value first.
Regroup when the ones or tens digit of the subtrahend is greater than the ones or tens digit of the minuend.
If the tens digit of the minuend is a zero, a hundred is regrouped before a ten is regrouped.

Common misconception

Pupils may struggle to regroup in the ones and tens when the tens digit is zero.

Explain that pupils may need to regroup from the hundreds first, and then regroup in the ones. They still need to start with the numbers with the smallest place value. When crossing out, pupils need to cross out the '10' tens and replace with 9

Keywords

Column subtraction - Column subtraction is a way of subtracting numbers by writing a number below another.
Regrouping - The process of unitising and exchanging between place values is known as regrouping.