1. Unit 2. Day 14.

2. Please get out paper for today’s lesson
Name
Date
Period
Topic: Multiplying & Dividing Rational Numbers
7.NS.A.2 Apply and extend previous understandings of multiplication and division and of fractions to multiply and divide rational numbers

3. ∙ Example A: − 7 20 ∙ = = = − 35 100 8 15 8 15 56 2∙2∙2∙7 14 − − 300
−0.35
8 15 ∙
−0.35
8 15 −
8 15
− 7 20 56
2∙2∙2∙7 14 ∙ = − = − = −
300
2∙2∙3∙5∙5 75

4. ÷ ÷ Example B: − 7 20 ÷ = = = − = 8 15 − 35 100 8 15 − 7 160
8 15 ÷ −0.35
8 15
Example B: ÷
−0.35
8 15 −
8 15
− 7 20
8 15
− 7 20 ÷ ÷ − 7
160
2∙2∙2∙2∙2∙5
8 15 = − = − ∙ 20
105
3∙5∙7 32 − = − = 21

5. 0.4÷−1 1 3
Example C*:
8 9 −0.6
Example D*:

6. ÷ ÷ Example C*: − 4 3 ÷ = = = 4 10 − 4 3 2 5 − 4 2∙3 3 2 5 6 − − ∙
0.4÷−1 1 3
−1 1 3
Example C*: ÷
0.4
4 10
− 4 3
2 5
− 4 3
2 5
− 4 3 ÷ ÷ − 4
2∙3 3
2 5 6 − = − = − = ∙
2∙2∙5 10 3 20

7. ∙ Example D*: − 3 5 ∙ = = = − 6 10 8 9 8 9 24 2∙2∙2∙3 8 − − 45 3∙3∙5
8 9 −0.6
8 9 ∙
−0.6
8 9
− 6 10
8 9
− 3 5 24
2∙2∙2∙3 8 ∙ = − = − = − 45
3∙3∙5 15

8. The Commutative Property
2+3
3+2
2−3
3−2

9. − −0.45
− 4 25
Commutative?
−0.45 − 4 25
− 4 25 ∙
−0.45
−0.45 ∙
− 4 25 − −
− 4 25
− 4 25
− 9 20
− 9 20
− 4 25 36 36 ∙ = ∙ =
500
500
2∙2∙3∙3
2∙2∙3∙3
2∙2∙5∙5∙5
2∙2∙5∙5∙5 9 9
125
125

10. − ÷ −0.45
− 4 25
Commutative?
−0.45 ÷ − 4 25
− 4 25 ÷ ÷
−0.45
−0.45
− 4 25 − −
− 4 25
− 9 20
− 20 9
− 9 20
− 4 25
− 25 4
− 4 25 80
225 ÷ ∙ = ÷ ∙ =
225 80
3∙3∙5∙5
2∙2∙2∙2∙5
3∙3∙5∙5
2∙2∙2∙2∙5 16 45 = =
0.3 5
2.8125 45 16

12. (Using Commutative Property of Multiplication)
Clever Math
(Using Commutative Property of Multiplication)

13. Example E:
4 ∙ ∙ −8 ∙ 9 ∙ − 1 2
1 3
− 1 2 4 −8 9
− 8 1
∙ ∙ ∙ ∙
8 2
1 3 ∙ ∙ 4
9 1 4 ∙ 9
9 3
∙ 4 ∙ 4 3 12
∙ 4 48

14. Example F:
1 ÷ ∙ −8 ∙ 3 ÷ − 1 2
− 2 1
∙ −8 ∙ 3
3 2
3 2
− 2 1 1 ∙ −8 3 ∙
∙ ∙ ∙ ∙
− 6 2 −3
∙ −8 ∙ 3∙ 1 24
∙ 3∙ 1
72∙ 1 72