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Negative Numbers

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Negative Numbers

-5

-4

-3

-2

-1

0

1

2

3

4

5

counting negatively

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

0

1

2

3

4

5

counting negatively

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

0

1

2

3

4

5

counting negatively

counting positively

Remember:

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

0

1

2

3

4

5

counting negatively

counting positively

Example:

Which word, “bigger” or “smaller”, would fit correctly

In each of these gaps?

smaller

-7 is ___________than -1

+62 is ___________than -71

-136 is ___________than -36

bigger

smaller

Why do negative numbers "get bigger"?

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

m

s

w

e

-4

-2

0

2

4

Let's Practice

-10

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.

o

Spring 7 C

o

o

Fall -4 C

Winter -12 C

If it helps you remember, think about the weather. As

temperature gets lower the negative numbers seem to

get bigger.

Temperature increase and decrease

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

temperature could be 3 C. By lunchtime it is up

to 10 C.

o

o

This is a

temperature

increase of

7 C.

15

15

10

10

5

5

o

0

0

-5

-5

Example:

In the early afternoon the temperature is 15 C. By early

evening the temperature goes down to 12 C.

o

o

15

This is a

temperature

decrease of

3 C.

15

10

10

5

5

0

o

0

-5

-5

During winter the early morning temperature could

be -3 C. By lunch it is up to 6 C.

o

o

o

o

o

From -3 C to 0 C is 3 C.

15

15

10

10

This is a temperature

increase of 9 C.

5

5

o

0

0

-5

-5

o

o

o

From 0 C to 6 C is a further 6 C.

o

o

The total of 3 C + 6 C makes 9 C.

o

But what happens if we have negative temperatures?

Example:

In the early afternoon the temperature is 3 C. By early

evening the temperature goes down to -5 C.

o

o

15

o

o

o

From 3 C to 0 C is 3 C.

15

10

10

5

0

5

0

-5

This is a temperature

decrease of 8 C.

-5

o

o

o

o

The total of 3 C + 5 C makes 8 C.

o

o

o

From 0 C to -5 C is a further 5 C.

14

10

o

2 C

6

o

C

Let's Practice

What temperature is shown

on the thermometer?

35

25

o

-5 C

10

0

o

C

What temperature is shown

on the thermometer?