Mathematics

Intermediate

50 mins

Teacher/Student led

Learning Goals

Learning Outcomes

Lesson Files

+65 XP

What you need:
IWB/Projector/Large Screen

Written Subtraction of 3-digit Numbers

Learn how to subtract 3-digit numbers by renaming column by column from right to left, including how to handle cases where you must rename across a zero.

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1 Getting Started
2 Watch and Notice
3 Try It Together
4 Set Out the Columns in Your Copy
5 Class Challenge
Pupil practice

1 - Getting Started ~4 mins

Illustration for Getting Started Here is a subtraction set out in neat columns: 423 take away 156.

Tip

Look at the units column first. It says 3 take away 6. Is there a wrinkle already? Hands up: which columns in this one do you think will need us to rename before we can take away?

👇 Mark your steps as done as you complete them.

+5 XP

2 - Watch and Notice ~9 mins

Watch the interactive work through four subtractions, one at a time, always starting in the units column. Each one needs a little more renaming than the last. Watch what happens when a column runs short.

👇 Mark your steps as done as you complete them.

+10 XP

3 - Try It Together ~8 mins

First I'll sketch 275 take away 132 on the board and we'll say each column aloud as we fill it in — this one is gentle, and every top digit is big enough, so no renaming.

Key point

Then we'll use the tool for 364 take away 138. This one makes us rename, so we'll work from the units first and decide whether to rename before we take away.

Try it together: 364 − 138

+15 XP

4 - Set Out the Columns in Your Copy ~3 mins

COPYBOOK MOMENT

First we will check one subtraction together on the board so you can see exactly how the add-back works. We already know 368 take away 142 is 226. Now add the answer back to the smaller number, column by column: 226 + 142. Units 6 + 2 = 8, tens 2 + 4 = 6, hundreds 2 + 1 = 3. We land on 368, the top number, so the subtraction is correct.

In your maths copy, set out these two subtractions in hundreds, tens and units columns, one under the other, and work each one:

526 − 248
703 − 365

Rename where you must, and cross out and drop the digit next door when you rename. When you finish, check each answer the same way we just did: add it back to the smaller number and you should land on the top number again.

+10 XP

5 - Class Challenge ~10 mins

Now we'll work through some more subtractions together, each one a little trickier than the last: 486 take away 253, then 473 take away 128, then 521 take away 276, then 800 take away 347. The last one has a zero waiting to catch us out, so we'll say the renaming aloud before we fill it in.

Column subtraction challenge

+15 XP

Pupil practice

Module 2 · The Four Operations: Mental and Written Number

Lesson 19 · Written Subtraction of 3-digit Numbers

Download Activity Book page (PDF)

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