Subtract two 3-digit numbers

Learning focus

In this lesson, you will learn how to subtract two three-digit numbers.

The lesson includes:

  • one catch-up quiz
  • one learning summary
  • one video
  • two interactive activities
  • two worksheets

Quiz

Test your knowledge of subtracting two 3-digit numbers in this quick quiz.

Learn

Do you know how to subtract numbers from each other? Find out by watching this short animation featuring a terror from the deep from KS2 Maths.

Checklist

When subtracting 3 digit numbers it is useful to use this checklist:

  • Write the numbers in columns. Separate the numbers into ones, tens and hundreds. Always start with the ones first.

  • Estimate first and check afterwards. Estimate a rough answer first, then work out your actual answer.

  • Subtraction is the opposite to addition. So subtraction can always be checked by adding. Check that 182 - 37 = 145 by doing the sum: 145 + 37 = 182

  • Look out for these words in problems: take away, difference, less than, minus, decrease, fewer than, reduce. They all mean subtraction.

Column subtraction

The column method is a great way to do subtraction.

Example 1

  • What is 548 - 125?
Start from the ones column: 8 - 5 = 3

Start from the ones column: 8 - 5 = 3

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Example 2

  • What is 343 - 237?

When using a place value column to subtract two large numbers, sometimes the second number will be larger than the first. This means it cannot be directly subtracted. You need to exchange a digit from the next column.

This example shows how it works:

Start from the ones column: 3 - 7

Start from the ones column: 3 - 7

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The column method can be applied to help you solve word problems. Remember to look for the words that mean subtraction.

Example 3

  • Lottie has £628 to spend. She buys a new bike which costs £446. How much money does Lottie have left?

The word left tells you that this is a subtraction problem.

Start with the ones column and subtract the two numbers. 8 - 6 =  2

Start with the ones column and subtract the two numbers. 8 - 6 = 2

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Practise

Activity 1

Simple subtraction

Click on the image below to see if you can subtract the numbers correctly.

Activity 2

Some more simple subtraction

Click on the image below to see if you can subtract the numbers correctly.

Play

Play Guardians: Defenders of Mathematica to learn more and sharpen your skills on this topic.

Guardians: Defenders of Mathematica

There's more to learn

Have a look at these other resources.

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