Adding three-digit numbers

Home learning focus

In this lesson, you will learn how to add three-digit numbers together.

This lesson includes:

  • two videos
  • one online activity
  • two activity sheets

Learn

First, let’s find out a bit about the method for adding numbers together using number columns. Watch this short animation featuring a hive of helpful bees from KS2 Maths.

When writing down sums, separate the numbers into ones, tens and hundreds. List the numbers in a column and always start adding with the ones first.

  • Estimate first and check afterwards - it's a good idea to estimate a rough answer first and then check your actual answer.
  • Order doesn't matter - remember that 345 + 129 is the same as 129 + 345.
  • Key words - look out for these words in problems: total, sum, altogether, more. They all indicate an addition calculation.

Column addition

Numbers can be added together using the column method which involves writing one number underneath the other.

What is 343 + 315?

Start from the ones column: 3 + 5 = 8

Start from the ones column: 3 + 5 = 8

1 of 4

If the two numbers in a place value column add up to a number greater than 9, you must carry a digit.

What is 343 + 329?

Start from the ones column: 3 + 9 = 12, place a 2 in the ones column and carry 10 to the tens column by placing a 1

Start from the ones column: 3 + 9 = 12, place a 2 in the ones column and carry 10 to the tens column by placing a 1 below

1 of 4

Practise

Activity 1

Hive maths

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

Activity 2

Adding three-digit numbers

Test your knowledge of three-digit numbers with this worksheet from Twinkl.

Adding three-digit numbers

Click here for the answer sheet.

Activity 3

Three-digit numbers game

Put your knowledge of three-digit numbers through its paces with this fun active learning game from Move & Learn.

All you need is a pack of playing cards, some paper, a pen and a container.

Physical and thinking challenges

There's more to learn

Have a look at these other resources around the BBC and the web.

KS2 Maths
Bitesize Daily lessons
Numbertime
audio