Transcript Negative Numbers

-5
-4 -3 -2 -1
counting negatively
0
1
2
3
4
5
counting positively
Any number above zero is a positive number. Positive
numbers are written with no sign or a + sign in front of them
and they are counted from zero to the right.
-5
-4 -3 -2 -1
counting negatively
0
1
2
3
4
5
counting positively
Any number below zero is a negative number. Negative
numbers are written with a - sign in front of them
and they are counted from zero to the left.
Always look at the sign in front of a number to see if it is
positive or negative.
-5
-4 -3 -2 -1
counting negatively
0
1
2
3
4
5
counting positively
Positive numbers get bigger the further we move right, so 5
is bigger than 2.
Negative numbers get smaller the further we move left, so -5
is smaller than -2.
-5
-4 -3 -2 -1
counting negatively
0
1
2
3
4
5
counting positively
Which word, “bigger” or “smaller”, would fit correctly
In each of these gaps?
smaller
-7 is ___________than
-1
bigger
+62 is ___________than
-71
smaller
-136 is ___________than
-36
As you extend a number line showing negative numbers, they
seem to get “bigger.”
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
1
2
The numbers seem to increase in value as they go down
the number line.
But as the negative number gets bigger, the value gets
lower. -10 is a larger number than -5, so it is further below
zero. If you look at the number line you can see that -10
is less than -5.
a d
-10
m
s
-4 -2
0
2
4
w e
8
What value is letter w?
What value is letter a?
Which value is bigger -10 or 8?
Even though 10 is a bigger number than 8, 8 is bigger because 10 is negative.
If it helps you remember, think about the weather. As
temperature gets lower the negative numbers seem to
get bigger.
o
Spring 7 C
o
Fall -4 C
o
Winter -12 C
When the weather changes the temperature can go up or
down. If a temperature goes up, gets warmer, it is a
temperature increase. If a temperature goes down, gets
colder, it is a temperature decrease.
During the summer when you wake up, the morning
o
temperature
could
be
3
C. By lunchtime it is up
o
to 10 C.
15
15
10
10
5
5
0
0
-5
-5
This is a
temperature
increase of
o
7 C.
o
In the early afternoon the temperature is 15 C. By early
o
evening the temperature goes down to 12 C.
15
15
10
10
5
5
0
0
-5
-5
This is a
temperature
decrease of
o
3 C.
But what happens if we have negative temperatures?
Example:
During winter the early morning temperature could
o
o
be -3 C. By lunch it is up to 6 C.
o
15
o
15
10
From 0 C to 6 C is a further 6 C.
o
10
o
From -3 C to 0 C is 3 C.
o
o
o
5
5
0
0
-5
-5
o
The total of 3oC + 6 C makes 9 C.
This is a temperature
o
increase of 9 C.
o
In the early afternoon the temperature is 3 C. By early
o
evening the temperature goes down to -5 C.
15
10
5
15
10
5
0
0
-5
-5
o
o
o
From 3 C to 0 C is 3 C.
o
o
o
From 0 C to -5 C is a further 5 C.
o
o
o
The total of 3 C + 5 C makes 8 C.
This is a temperature
o
decrease of 8 C.
14
What temperature is shown
on the thermometer?
10
o
2C
6
C
o
35
What temperature is shown
on the thermometer?
25
10
o
-5 C
0
C
o