Directed Numbers

Objective: Be able to add and subtract directed numbers.

First, you have to know the number line!

If you remember what the number line looks like you will find this easy!

87654321

-1-2-3-4-5-6-7-8-9

0

Let’s look at a question

Work out

+6 + -3What does this mean?

The first part tells you where to start on the number line.

The symbols tell you what to do.

If they are the same, you add.

If they are different, you subtract

The last number tells you by how much.

Let’s do it

+6 + -3

87654321

-1-2-3-4-5-6-7-8-9

0

Start here

They are different, so subtract… … this

much

One!Two!Three!

So there’s your

answer, 3

+6 + -3 = 3

Here’s another …

-4 - -9

87654321

-1-2-3-4-5-6-7-8-9

0

Start here

They are the same, so we add… … this

much So there’s your

answer, 5

Here’s another …

-4 - -9

87654321

-1-2-3-4-5-6-7-8-9

0

Start here

They are the same, so we add… … this

much So there’s your

answer, 5