Learn on PengienVision, Mathematics, Grade 4Chapter 4: Use Strategies and Properties to Multiply by 2-Digit Numbers

Lesson 1: Multiply Multiples of 10

Property.

Section 1

Multiplying Using Unit Form

Property

To multiply numbers in unit form, multiply the digits and then multiply the place value units.

(a tens)×(b tens)=(a×b) hundreds(a \text{ tens}) \times (b \text{ tens}) = (a \times b) \text{ hundreds}
(a tens)×(b ones)=(a×b) tens(a \text{ tens}) \times (b \text{ ones}) = (a \times b) \text{ tens}

Examples

Section 2

Multiply Multiples of 10 by Decomposing Factors

Property

To multiply two-digit multiples of 10, you can decompose each number, then use the associative property to regroup the factors.

(a×10)×(b×10)=(a×b)×(10×10)(a \times 10) \times (b \times 10) = (a \times b) \times (10 \times 10)

This is the same as multiplying the units: a tens×b tens=(a×b) hundredsa \text{ tens} \times b \text{ tens} = (a \times b) \text{ hundreds}.

Examples

Section 3

Multiplying When the Basic Fact Ends in Zero

Property

When multiplying multiples of 10, first find the product of the basic fact. Then, annex (attach) all the zeros from the original factors to the end of that product, even if the product of the basic fact already ends in a zero.

Examples

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Chapter 4: Use Strategies and Properties to Multiply by 2-Digit Numbers

  1. Lesson 1Current

    Lesson 1: Multiply Multiples of 10

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  2. Lesson 2

    Lesson 2: Use Models to Multiply 2-Digit Numbers by Multiples of 10

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  3. Lesson 3

    Lesson 3: Estimate: Use Rounding or Compatible Numbers

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  4. Lesson 4

    Lesson 4: Arrays and Partial Products

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  5. Lesson 5

    Lesson 5: Area Models and Partial Products

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  6. Lesson 6

    Lesson 6: Use Partial Products to Multiply by 2-Digit Numbers

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Lesson overview

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Section 1

Multiplying Using Unit Form

Property

To multiply numbers in unit form, multiply the digits and then multiply the place value units.

(a tens)×(b tens)=(a×b) hundreds(a \text{ tens}) \times (b \text{ tens}) = (a \times b) \text{ hundreds}
(a tens)×(b ones)=(a×b) tens(a \text{ tens}) \times (b \text{ ones}) = (a \times b) \text{ tens}

Examples

Section 2

Multiply Multiples of 10 by Decomposing Factors

Property

To multiply two-digit multiples of 10, you can decompose each number, then use the associative property to regroup the factors.

(a×10)×(b×10)=(a×b)×(10×10)(a \times 10) \times (b \times 10) = (a \times b) \times (10 \times 10)

This is the same as multiplying the units: a tens×b tens=(a×b) hundredsa \text{ tens} \times b \text{ tens} = (a \times b) \text{ hundreds}.

Examples

Section 3

Multiplying When the Basic Fact Ends in Zero

Property

When multiplying multiples of 10, first find the product of the basic fact. Then, annex (attach) all the zeros from the original factors to the end of that product, even if the product of the basic fact already ends in a zero.

Examples

Book overview

Jump across lessons in the current chapter without opening the full course modal.

Continue this chapter

Chapter 4: Use Strategies and Properties to Multiply by 2-Digit Numbers

  1. Lesson 1Current

    Lesson 1: Multiply Multiples of 10

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  2. Lesson 2

    Lesson 2: Use Models to Multiply 2-Digit Numbers by Multiples of 10

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  3. Lesson 3

    Lesson 3: Estimate: Use Rounding or Compatible Numbers

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  4. Lesson 4

    Lesson 4: Arrays and Partial Products

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  5. Lesson 5

    Lesson 5: Area Models and Partial Products

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  6. Lesson 6

    Lesson 6: Use Partial Products to Multiply by 2-Digit Numbers

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