Learn on PengiEureka Math, Grade 4Chapter 14: Reasoning with Divisibility

Lesson 1: Find factor pairs for numbers to 100, and use understanding of factors to define prime and composite.

This Grade 4 Eureka Math lesson introduces students to finding factor pairs for numbers up to 100 using arrays and area models, then builds on that understanding to define prime and composite numbers. Students practice identifying all factor pairs of a given number by systematically connecting pairs such as 1 and 18, 2 and 9, and 3 and 6, learning to confirm when they have found every pair. The lesson is part of Chapter 14: Reasoning with Divisibility and connects multiplication fluency to foundational number theory concepts.

Section 1

Defining Factors and Factor Pairs

Property

Factors are numbers that are multiplied together to get a product.
If a×b=ca \times b = c, then aa and bb are factors of cc.
The set (a,b)(a, b) is called a factor pair of cc.

Examples

Section 2

Defining Prime and Composite Numbers

Property

A prime number is a whole number greater than 1 that has exactly two factors: 1 and itself.
A composite number is a whole number that has more than two factors.
The number 1 is a special case and is neither prime nor composite because it has only one factor.

Examples

Book overview

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Chapter 14: Reasoning with Divisibility

  1. Lesson 1Current

    Lesson 1: Find factor pairs for numbers to 100, and use understanding of factors to define prime and composite.

  2. Lesson 2

    Lesson 2: Use division and the associative property to test for factors and observe patterns.

  3. Lesson 3

    Lesson 3: Determine if a whole number is a multiple of another number.

  4. Lesson 4

    Lesson 4: Explore properties of prime and composite numbers to 100 by using multiples.

Lesson overview

Expand to review the lesson summary and core properties.

Expand

Section 1

Defining Factors and Factor Pairs

Property

Factors are numbers that are multiplied together to get a product.
If a×b=ca \times b = c, then aa and bb are factors of cc.
The set (a,b)(a, b) is called a factor pair of cc.

Examples

Section 2

Defining Prime and Composite Numbers

Property

A prime number is a whole number greater than 1 that has exactly two factors: 1 and itself.
A composite number is a whole number that has more than two factors.
The number 1 is a special case and is neither prime nor composite because it has only one factor.

Examples

Book overview

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

Continue this chapter

Chapter 14: Reasoning with Divisibility

  1. Lesson 1Current

    Lesson 1: Find factor pairs for numbers to 100, and use understanding of factors to define prime and composite.

  2. Lesson 2

    Lesson 2: Use division and the associative property to test for factors and observe patterns.

  3. Lesson 3

    Lesson 3: Determine if a whole number is a multiple of another number.

  4. Lesson 4

    Lesson 4: Explore properties of prime and composite numbers to 100 by using multiples.