1. 1.4-5: Multiplying Integers: Basic Rules

2. Ways to Express multiplication Remember: All of these mean the same thing: Five times four 5 × 4 5 · 4 5(4)

3. Multiplying on a Number Line: Positive Integers 5(3)

4. Multiplying on a Number Line: Positive times Negative 5(–3) –5(3)

5. Multiplying on a Number Line: Negative times Negative –5(–3)

6. Rules for Multiplying Integers If the signs of the factors are the same, the product is positive: 3(2) = 6–3(–2) = 6 If the signs of the factors are different, the product is negative: –3(2) = –63(–2) = –6

7. Dividing Integers Remember, division can be written like this: 32 ÷ 16...or like this:

8. Dividing Integers To divide integers, follow the same rules as for multiplying: Negative divided by negative has positive result. Positive divided by negative or negative divided by positive …has negative result.

9. IMPORTANT: Division by Zero Division by zero is undefined (not defined) in our everyday number system. In other words, “3 ÷ 0” has no answer. If you are supposed to evaluate an expression such as –10 ÷ 0 You should write this answer: undefined

10. Try It Yourself 1.3(8) 2.3(–8) 3.–3(–8) 4.–3(8) 5.2(–4) 6.–2(–4) 7.–2(4) 8.–3(0) 9.–10(10) 10.0(–15) 11.–10(–10) 12.–5(–5) 13.–5(5) 14.5(–4)