Learn on PengiEureka Math, Grade 4Chapter 16: Multiplication of Two-Digit by Two-Digit Numbers

Lesson 3: Multiply two-digit by two-digit numbers using four partial products.

In this Grade 4 Eureka Math lesson, students learn to multiply two-digit by two-digit numbers by applying the distributive property to generate four partial products using an area model. Students break each factor into tens and ones, then find and sum the four smaller products — ones times ones, ones times tens, tens times ones, and tens times tens — to find the total. This lesson builds directly on prior work with multiples of 10 and prepares students for efficient two-digit multiplication strategies.

Section 1

Representing Multiplication with an Array

Property

To multiply two two-digit numbers, we can decompose each number into tens and ones and use the distributive property.
This can be visualized with an array, where the total area is the sum of four smaller areas, known as partial products.
For factors (a+b)(a+b) and (c+d)(c+d):

(a+b)×(c+d)=(a×c)+(a×d)+(b×c)+(b×d)(a + b) \times (c + d) = (a \times c) + (a \times d) + (b \times c) + (b \times d)

Examples

Section 2

Recording Partial Products Vertically

Property

To find the total product, the four partial products are recorded vertically, aligned by place value, and then added together.

Examples

Book overview

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Chapter 16: Multiplication of Two-Digit by Two-Digit Numbers

  1. Lesson 1

    Lesson 1: Multiply two-digit multiples of 10 by two-digit numbers using a place value chart.

  2. Lesson 2

    Lesson 2: Multiply two-digit multiples of 10 by two-digit numbers using the area model.

  3. Lesson 3Current

    Lesson 3: Multiply two-digit by two-digit numbers using four partial products.

  4. Lesson 4

    Lesson 4: Transition from four partial products to the standard algorithm for two-digit by two-digit multiplication.

  5. Lesson 5

    Lesson 5: Transition from four partial products to the standard algorithm for two-digit by two-digit multiplication.

Lesson overview

Expand to review the lesson summary and core properties.

Expand

Section 1

Representing Multiplication with an Array

Property

To multiply two two-digit numbers, we can decompose each number into tens and ones and use the distributive property.
This can be visualized with an array, where the total area is the sum of four smaller areas, known as partial products.
For factors (a+b)(a+b) and (c+d)(c+d):

(a+b)×(c+d)=(a×c)+(a×d)+(b×c)+(b×d)(a + b) \times (c + d) = (a \times c) + (a \times d) + (b \times c) + (b \times d)

Examples

Section 2

Recording Partial Products Vertically

Property

To find the total product, the four partial products are recorded vertically, aligned by place value, and then added together.

Examples

Book overview

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

Continue this chapter

Chapter 16: Multiplication of Two-Digit by Two-Digit Numbers

  1. Lesson 1

    Lesson 1: Multiply two-digit multiples of 10 by two-digit numbers using a place value chart.

  2. Lesson 2

    Lesson 2: Multiply two-digit multiples of 10 by two-digit numbers using the area model.

  3. Lesson 3Current

    Lesson 3: Multiply two-digit by two-digit numbers using four partial products.

  4. Lesson 4

    Lesson 4: Transition from four partial products to the standard algorithm for two-digit by two-digit multiplication.

  5. Lesson 5

    Lesson 5: Transition from four partial products to the standard algorithm for two-digit by two-digit multiplication.