# Practise Your Column Addition and Subtraction Skills

In this worksheet, students will use a formal written method to add and subtract numbers with up to 3 digits (including exchanging).

Key stage:  KS 2

Curriculum topic:   Number: Addition and Subtraction

Curriculum subtopic:   Use Written Addition/Subtraction to Three Digits

Difficulty level:

#### Worksheet Overview

When we are asked to add or subtract numbers such as 15 + 5 or 15 - 5, we can often work out the answer mentally ( in our heads ).

However, when we are given questions with bigger numbers we usually need to use a written method.

In this activity, we will look at the columnar method to add and subtract numbers.

Let's have a look at how we can use the method to add 342 + 442

First, we write the numbers in columns under the correct unit (hundreds, tens, ones).

H T O

3 4 2

4 4 2

We need to add an addition symbol (+) to show that we are adding.

Starting at the right-hand column (ones), we add each column and write the answers underneath.

H T O

3 4 2

4 4 2

7 8 4

342 + 442 = 784

Here is another example. This time we will need to exchange (also known as 'carrying').

Remember to include a + sign.

H T O

6 6 6

3 2 5

9 911

When we add 6 and 5 the answer is 11.

We can partition this into 10 and 1.

The ten moves into the tens column ( see the small 1 which represents 1 ten). We can think of this little 1 as being 'on the doorstep' of the tens column!

The one stays in the ones column.

We then move to the tens column and add 6 + 2 = 8 and then add on the 1 that was left on the 'doorstep': 8 + 1 = 9

Finally, the hundreds: 6 + 3 = 9

Here's our answer: 666 + 325 = 991

Now let's look at subtraction.

564 - 352

Set it out carefully in columns, but don't forget to include a subtraction symbol (-) so we know what we're trying to do!

H T O

5 6 4

3 5 2

2 1 2

564 - 352 = 212

Again, we start with the ones column, but this time we subtract the bottom number from the top (4 - 2 is not the same as 2 - 4).

It is important that we remember this!

Now, let's have a go at subtracting with exchanging, also known as 'borrowing'.

H T O

4514 5

2 5 2

2 9 3

The ones: first, we subtract 2 from 5 to get 3

The tens: next, we can't subtract 5 from 4, so we exchange (or borrow) one hundred for 10 lots of ten (500 becomes 400 and 40 becomes 140)

Now, we can subtract 5 (50) from 14 (140) to get 9 (90)

The hundreds: finally, we subtract 2 (200) from 4 (400) to get 2 (200)

Phew, that was a lot to do!

Now, why don't you have a go at answering some questions using the columnar method? Good luck!

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