All the solutions provided inÂ **McGraw Hill My Math Grade 4 Answer Key PDF Chapter 8 Lesson 1 Factors and Multiples **will give you a clear idea of the concepts.

## McGraw-Hill My Math Grade 4 Answer Key Chapter 8 Lesson 1 Factors and Multiples

The factors of a number help us determine whether a number is prime, composite, or neither.

**Math in My World
**

**Example 1**

Blair is arranging 18 cupcakes on a shelf. Find the factors of 18. Use arrays to find the factors.

So, the factors of 18 are __________, __________, __________, __________, __________, and __________,

Since 18 has more than two factors, it is a composite number.

Answer:

Explanation:

Number of cupcakes Blair is arranging on a shelf = 18.

Factors of 18:

1 Ă— 18 = 18.

2 Ă— 9 = 18.

3 Ă— 6 = 18.

6 Ă— 3 = 18.

9 Ă— 2 = 18.

So, the factors of 18 are 2, 3, 6, 9, 18, and 1.

Since 18 has more than two factors, it is a composite number.

**Example 2
**Sarah is at the park. She counts 73 kites. Write the factors of 73 on the kite. Tell whether it is prime, composite, or neither.

The factors of 73 are ____________ and _____________.

Since 73 has exactly two distinct factors, it is a ___________ number.

Answer:

The factors of 73 are 1 andÂ 73.

Since 73 has exactly two distinct factors, it is a prime number.

Explanation:

Number of kites she counts = 73.

Factors of 73:

1 Ă— 73 = 73.

A prime number isÂ a whole number greater than 1 whose only factors are 1 and itself.

In Mathematics, composite numbers areÂ numbers that have more than two factors.

**Example 3
**Tell whether 1 is prime, composite, or neither.

Find the factors of 1.

1 Ă— 1

Since 1 only has one distinct factor, it is __________________.

Answer:

1 is a prime number.

Explanation:

1 Ă— 1 = 1.

Factors of 1: 1 and itself.

Since 1 only has one distinct factor, it is prime number..

**Talk Math
**Identify the smallest prime number. Explain how you know this is the smallest prime number.

Answer:

1 is the smallest prime number.

Explanation:

A prime number is a number that has only two factors, that is 1 and the number itself. The smallest non-zero number is 1.Â 1 has only one factor which is 1 itself.

**Guided Practice
**

**Tell whether each number is prime, composite, or neither.**

Question 1.

5

Answer:

5 is a prime number.

Explanation:

Number 5:

Factors of 5:

1 Ă— 5 = 5.

A prime number is a number that has only two factors, that is 1 and the number itself.

Question 2.

15

Answer:

15Â is a composite number.

Explanation:

Number 15:

Factors of 15:

1 Ă— 15 = 15.

3 Ă— 5 = 15.

In Mathematics, composite numbers areÂ numbers that have more than two factors.

Question 3.

21

Answer:

21 is a composite number.

Explanation:

Number 21:

Factors of 21:

1 Ă— 21 = 21.

3 Ă— 7 = 21.

In Mathematics, composite numbers areÂ numbers that have more than two factors.

Question 4.

31

Answer:

31 is a prime number.

Explanation:

Number 31:

Factors of 31:

1 Ă— 31 = 31.

A prime number is a number that has only two factors, that is 1 and the number itself.

Question 5.

26

Answer:

26 is a composite number.

Explanation:

Number 26:

Factors of 26:

1 Ă— 26 = 26.

2 Ă— 13 = 26.

In Mathematics, composite numbers areÂ numbers that have more than two factors.

Question 6.

61

Answer:

61 is a prime number.

Explanation:

Number 61:

Factors of 61:

1 Ă— 61 = 61.

A prime number is a number that has only two factors, that is 1 and the number itself.