Title: A' Directed Numbers'
1A. Directed Numbers.
A directed number is any number,
with a
or a - in front of it.
A number by itself is assumed positive.
2
-
2
( )
But it could have a sign in front
even with brackets.
The sign may be raised to the top left corner.
2A. Directed Numbers.
Natural numbers (counting numbers) are always
positive, Integers can be positive, negative, or
0.
-
-
2
-
2
( )
A negative number MUST have a - sign
With or without the brackets.
Or a - sign in the top left hand corner.
3The number line.
- Integers can be shown along a single number line.
8
-8
5
0
1
2
3
6
-1
-2
-3
-4
-5
-6
4
8 Infinity, a very big number!
If we start at 0, positive numbers increase to
the right.
Negative numbers decrease to the left of 0..
4Working with directed numbers.
8
-8
5
0
1
2
3
6
-1
-2
-3
-4
-5
-6
4
Fido is going to demonstrate working with
directed numbers. Instructions Large
move forward Raised okay
- move backward - do the
opposite
5Working with directed numbers.
Bark, bark!
8
-8
5
0
1
2
3
6
-1
-2
-3
-4
-5
-6
4
4 2
6
Start a 4
Move forward, okay, 2 places
6Working with directed numbers.
Bark, bark!
8
-8
5
0
1
2
3
6
-1
-2
-3
-4
-5
-6
4
So Fido moves forwards!
-3 - - 6
3
Start a -3
Move backward, do opposite, 6 places
7- When the signs were the same, Fido moved
- forward.
Add
Bark, bark
- -
Worth remembering
8Working with directed numbers.
Bark, bark!
8
-8
5
0
1
2
3
6
-1
-2
-3
-4
-5
-6
4
So Fido moves backwards!
5 - 2
3
Start a 5
Move forward, do opposite, 2 places
9Working with directed numbers.
Bark, bark!
8
-8
5
0
1
2
3
6
-1
-2
-3
-4
-5
-6
4
So Fido moves backwards!
3 - 2
1
Start a 3
Move backward, okay, 2 places
10- When the signs were different, Fido moved
- backward.
Subtract
-
-
Bark, bark
Worth remembering