1-4 Properties and Mental Math

9/20/11Warm UpFind each sum or product.

1. 17 + 15

2. 29 + 39

3. 8(24)

4. 7(12)

5. 3(91)

6. 6(15)

32

68

192

84

27390

1-4 Properties and Mental Math

Vocabulary

Commutative Property

18 + 9 = 9 + 18

15 x 2 = 2 x 15

1-4 Properties and Mental Math

Vocabulary

Associative Property

(17 + 2) + 9 = 17 + (2 + 9)

(12 x 2) x 4 = 12 x (2 x 4)

1-4 Properties and Mental Math

Simplify 17 + 5 + 3 + 15.

17 + 5 + 3 + 15 Look for sums that are multiples of 10

40

Use the Commutative Property. 17 + 3 + 5 + 15

(17 + 3) + (5 + 15)

Use mental math to add.

20 + 20

Use the Associative Property to make groups of compatible numbers.

1-4 Properties and Mental Math

Simplify 4 13 5.

4 13 5

Look for products that are multiples of 10

260

Use the Commutative Property.13 4 5

13 (4 5)

Use mental math to multiply.13 20

Use the Associative Property to group compatible numbers.

1-4 Properties and Mental Math

Simplify 12 + 5 + 8 + 5.

12 + 5 + 8 + 5 Look for sums that are multiples of 10

30

Use the Commutative Property.12 + 8 + 5 + 5

(12 + 8) + (5 + 5)

Use mental math to add.

20 + 10

Use the Associative Property to make groups of compatible numbers.

1-4 Properties and Mental Math

Vocabulary

Distributive Property

6(10 + 4) = (6 x 10) + (6 x 4)

1-4 Properties and Mental Math

Use the Distributive Property to find the product.

6 35

6 35 = 6 (30 + 5) “Break apart” 35 into 30 + 5.

= 210

Use the Distributive Property.= (6 30) + (6 5)

Use mental math to add.

= 180 + 30 Use mental math to multiply.

1-4 Properties and Mental Math

Use the Distributive Property to find the product.

9 87

9 87 = 9 (80 + 7) “Break apart” 87 into 80 + 7.

= 783

Use the Distributive Property.= (9 80) + (9 7)

Use mental math to add.

= 720 + 63 Use mental math to multiply.

1-4 Properties and Mental Math

Use the Distributive Property to find the product.

4 27

4 27 = 4 (20 + 7) “Break apart” 27 into 20 + 7.

= 108

Use the Distributive Property.= (4 20) + (4 7)

Use mental math to add.

= 80 + 28 Use mental math to multiply.

1-4 Properties and Mental Math

Lesson Quiz

Simplify.

1. 18 + 24 + 2 + 6 2. 10 5 3

3. 13 + 42 + 7 + 8

Use the Distributive Property to find each

product.

4. 8 12 5. 6 15

6. 5 34 7. 3 71

15050

70

96 90

170 213

1-4 Properties and Mental Math

Homework

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