For teaching and learning.

1. Directed Numbers
Objective: Be able to add
and subtract directed
numbers.

2. First, you have to know the
number line!
 If you
remember
what the
number line
looks like
you will find
this easy!
8
7
6
5
4
3
2
1
-1
-2
-3
-4
-5
-6
-7
-8
-9
0

3. Let’s look at a question
 Work out
+
6 + -
3
What 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.

4. Let’s do it
+
6 + -
3
8
7
6
5
4
3
2
1
-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

5. +
6 + -
3 = 3

6. Here’s another …
-
4 - -
9
8
7
6
5
4
3
2
1
-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

7. Here’s another …
-
4 - -
9
8
7
6
5
4
3
2
1
-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