1. Operations with Integers
1/30/13

2. What are Integers?
• Integers include all of the positive and
negative whole numbers, and zero.
Integers NOT Integers
3 -1.652
-4 ¾
12 2.5
0 0.7

3. Adding Integers
• On a number line:
1. Find the first number.
2. Move the distance of the second number.
a) Positive (+) numbers, move RIGHT
b) Negative (-) numbers, move LEFT
3. Where you land is the answer!
Example: 5 + 8

4. Examples:
• -4 + 1 =
• 7 + -9 =
• -8 + -4 =

5. Adding Integers Rules
• Use if you don’t have a number line.
• When the integers are:
▫ Both Positive: add the numbers
 Ex: 4 + 6 =
▫ Both Negative: add the numbers and
make it negative
 Ex: -2 + -5 =
▫ One Positive and One Negative: Subtract
and use the sign of the bigger number.
 Ex: -7 + 4 =

6. You Try!
• Add the integers.
• 12 + -4 =
• -8 + -9 =
• 2 + 13 =
• -11 + 5 =

7. Subtracting Integers 1/31/13
• Change the minus to a plus, and change the
sign of the number you are subtracting.
• Then add!
• Ex: -14 – 6 =
• Subtracting a Negative is the same as Adding!
• Ex: 12 – (-3) =

8. You Try!
• Subtract the integers.
• 17 – 4 =
• -8 – (-5) =
• 2 – 11 =
• -4 – 12 =

9. Multiplying Integers 2/1/13
• Sign Rules:
• Same signs -> Positive answer!
+ ∙ + = + and – ∙ – = +
• Ex: 2 ∙ 3 = 6 and -2 ∙ -3 = 6
• Different signs -> Negative answer!
+ ∙ – = – and – ∙ + = –
• Ex: 2 ∙ -3 = -6 and -2 ∙ 3 = -6

10. Examples:
• (5)(-12) =
• -14 x -8 =
• -23 ∙ 7 =

11. You Try!
• -9 x 17 =
• (-20)(-16) =
• 14 ∙ -5 =

12. Dividing Integers
• Sign rules are the same as multiplying!
• Examples:
• -16 ÷ -8 =
• =

13. You Try!
• -90 ÷ 6 =
•
• -57 ÷ 19 =