2b. neg and pos

Positive and Negative Numbers

Created by Richard Bull

Definition

• Positive number – a number greater than zero.

0 1 2 3 4 5 6

Definition

• Negative number – a number less than zero.

0 1 2 3 4 5 6-1-2-3-4-5-6

Negative Numbers Are Used to Measure Temperature

Negative Numbers Are Used to Show Debt

If you get a loan from the bank for £5,000.If you were to look at your bank balance it would show -£5,000.

Negative Numbers Are Used to Measure Under Sea Level

0102030

-10-20-30-40-50

Hint

• If you don’t see a negative or positive sign in front of a number it is positive.

9+

Integer Addition RulesRule #1•If the signs are the same, pretend the signs aren’t there and add them.

-9 + -5 = 14Rule #2•Ask which absolute number is bigger•now remember what sign it was, this is the sign for your answer

-

Solve the Problems• -3 + -5 =• 4 + 7 =• -6 + -7 = • 5 + 9 =• -9 + -9 =

-8

-18 14-1311

Integer Addition RulesRule #2•If the signs are different,

3 + -5 =pretend the signs aren’t there and subtract the smaller absolute number from the larger absolute number

5 - 3 = 2 Now look back at the original question and use the sign of the biggest absolute number for your answer

3 + -5 =

-

Solve These Problems•3 + -5 =• -4 + 7 =• (+3) + (-4) =• -6 + 7 = •5 + -9 =• -9 + 9 =

-25 – 3 = 2

0 -41

-13

9 – 9 = 0 9 – 5 = 47 – 6 = 1

4 – 3 = 17 – 4 = 3

One Way to Add Integers Is With a Number Line

0 1 2 3 4 5 6-1-2-3-4-5-6

When the number is positive countto the right.

When the number is negative countto the left.

+-

One Way to Add Integers Is With a Number Line

0 1 2 3 4 5 6-1-2-3-4-5-6+

-

+3 + -5 = -2

One Way to Add Integers Is With a Number Line

0 1 2 3 4 5 6-1-2-3-4-5-6+

-

+6 + -4 = +2

One Way to Add Integers Is With a Number Line

0 1 2 3 4 5 6-1-2-3-4-5-6+

-

+3 + -7 = -4

One Way to Add Integers Is With a Number Line

0 1 2 3 4 5 6-1-2-3-4-5-6-

+

-3 + +7 = +4

One Way to Add Integers Is With a Number Line

0 1 2 3 4 5 6-1-2-3-4-5-6-

+

-5 + +3 = +4

One Way to Add Integers Is With a Number Line

0 1 2 3 4 5 6-1-2-3-4-5-6-

+

-2 + +8 = +6

One Way to Add Integers Is With a Number Line

0 1 2 3 4 5 6-1-2-3-4-5-6-

+

-5 + +2 = -3

One Way to Add Integers Is With a Number Line

0 1 2 3 4 5 6-1-2-3-4-5-6-

-

-4 + -2 = -6

One Way to Add Integers Is With a Number Line

0 1 2 3 4 5 6-1-2-3-4-5-6-

-

-2 + -3 = -5

One Way to Add Integers Is With a Number Line

0 1 2 3 4 5 6-1-2-3-4-5-6-

-

-1 + -4 = -5

One Way to Add Integers Is With a Number Line

0 1 2 3 4 5 6-1-2-3-4-5-6-

-

-4 + -1 = -5

One Way to Add Integers Is With a Number Line

0 1 2 3 4 5 6-1-2-3-4-5-6+

+

4 + 1 = 5

One Way to Add Integers Is With a Number Line

0 1 2 3 4 5 6-1-2-3-4-5-6+

+

3 + 2 = 5

One Way to Add Integers Is With a Number Line

0 1 2 3 4 5 6-1-2-3-4-5-6+

+

1 + 5 = 6

Add integers with same signs:

Add the numbers and keep the sign

a)3 + 2 = 5 b) -4 + (-6) = -10

Add integers with different signs:

Subtract the (absolute values) and keep the sign of the sign of the absolute value

a) -7 + 4 = -3 b) 1 + (-9) = -8

Created by Richard Bull