Irving Middle School 1

Integers

Warm-Up Answer the Essential Question:

When and where must you be able to solve problems with positive and negative numbers in your life?

Write your answer on the white board(2min)

2

Integers

• Set of whole numbers ,their opposites, and zero.

• All numbers are found on number line.• They are counting numbers.

• No decimals or fractions• Signs are + and –Use number line to compare and order integers:• Notice that the numbers on a number line

increase as you move from left to right

Discuss with a partner the question:

•Name as many pairs of opposite words that can also represent opposite integers in real life.

Write your answer on the white board(2min)

3

The absolute value

positive

of an integer is the distance of the integer from 0 on a number line.

-10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10

-3 = 3

= 77

negative

5

Addition of Integers• To add integers:• Like signed numbers

• Add numbers and keep sign of addends

• Example -2 + -8 = -10 • Unlike signed numbers

• Subtract numbers and give answer the sign of the addend with larger absolute value.

• Example -2 + 8 = 6

6

Subtraction of Integers• Add instead of subtract• Change the sign of the

second number

• Use “Copy add opposite”

• A – B = A + - B• Example -12 – (-4 )=• -12 + 4 = -8

7

Multiplication of Integers

• Like Signs• Multiply and answer

is positive• Example: • -3 x -4= 12• Unlike signs• Multiply and answer

is negative• Example:• -3 x 5 = -15

8

Division of Integers

• Like Signs• Divide and answer is positive• Example: • -12/-4 = 3• Unlike signs• Divide and answer is negative• Example:• -15/3 = -5

9

The End

–Now you are ready for the…