Double digit multiplication turning point

5th Grade Two digit Multiplication

Multiplication

Multiplication Properties

• Commutative Property– When two numbers are multiplied together, the answer is the same

regardless of the order. 4 x 2 = 2 x 4

• Distributive Property– The sum of two numbers times a third is the same as first multiplying

the separate numbers by the number originally multiplied and then adding them. 4 x (6 + 3) = 4 x 6 + 4 x 3

• Associative Property– When three or more numbers are multiplied, the product is the same

regardless of how you group the factors. (2 x 3) x 4 = 2 x (3 x 4)

• Identity Property– The product of any number and one is that number. 5 x 1 = 5.

Multiplication Properties Practice

9 x 8 = 8 x 9

Commutative Property!

Multiplication Properties Practice

(1 x 10) x 1 = 1 x (10 x 1)

Associative Property!

Multiplication Properties Practice

6 x (11 + 12) = 6 x 11 + 6 x 12

Distributive Property!

Multiplication Properties Practice

2 x 8 = 8 x 2

Commutative Property!

Multiplication Properties Practice

534 x 1 = 534

Identity Property!

Estimating/Rounding• As Tyler said yesterday, “make your problem

easier!”– There are no set rules to rounding– The goal is to make the problem easy enough for

you to do it in your head!

Rounding Practice

283X 46

Rounding Practice

$ 78.02X $0.67

What is the product of 4 X 60?

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A. 24

B. 10

C. 240

D. 100

What is the product of 8 x 214?

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A. 1,600

B. 1,712

C. 32

D. 2,000

Estimate by Rounding:What is 68 x 45?

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A. 2,700

B. 2,400

C. 3,060

D. 3,500

Estimate by Rounding:What is the product of 18 x 92?

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A. 1,800

B. 1,656

C. 162

D. 110

Identify the multiplication property:12 x (5 x 7) = (12 x 5) x 7?

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A. Identity

B. Commutative

C. Product

D. Associative

Identify the multiplication property:71 x 43 x 95 = 43 x 95 x 71

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A. Identity

B. Commutative

C. Product

D. Associative

Identify the multiplication property:271 x 1 = 271

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A. Commutative

B. Identity

C. Product

D. Associative

Val bought 12 DVDs at $18 each. Estimate the total cost of the DVDs.

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A. $240

B. $200

C. $36

D. $12

Matilda earns $11 an hour for babysitting. How much will she earn in 3 weeks if she

babysits 15 hours each week?

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A. $45

B. $33

C. $165

D. $495

Grace completed practice math problems for 1.5 hours a day every day this week. She

solved 8 problems an hour, how many problems did she complete?

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A. 8

B. 12

C. 84

D. 27

Grapefruits cost $2.49 per pound. If Jenny bought 7 pounds of grapefruit at the market this morning, about how much did it cost?

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A. $7.00

B. $17.43

C. $2.49

D. $17.50

Which answer means, “the answer to a multiplication problem”?

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A. Distributive Property

B. Factor

C. Associative property

D. Product

Which answer is, “the property which states that the grouping of the factors does not change the product”.

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A. Distributive Property

B. Factor

C. Associative Property

D. Product

Which answer means: “a number that divides into a whole number evenly. Also, a number

that is multiplied by another number”.

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A. Product

B. Associative Property

C. Factor

D. Distributive Property

Which word is, “the property that states that to multiply a sum by a number, you can multiply each addend by the same number and add the

products” ?

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A. Factor

B. Associative Property

C. Distributive Property

D. Product