Prime Factorization Worksheets

**Page 11**

101.

What is a composite number?

a. | Number having two factors, one and itself | ||

b. | Number having infinite number of factors | ||

c. | Number having only two factors | ||

d. | Number having more than two factors |

Correct answer : (4)

102.

List all the prime numbers greater than 20 and less than 30.

a. | 17 and 19 | ||

b. | 23 and 29 | ||

c. | 23, 31, 29 | ||

d. | 23 and 27 |

List of prime numbers greater than 20 and less than 30 are 23 and 29.

Correct answer : (2)

103.

Is 1 a prime number or a composite number?

a. | Prime | ||

b. | Composite | ||

c. | Both prime and composite | ||

d. | Neither prime nor composite |

A number that has more than two factors is called a composite number.

To find whether 1 is a prime number or composite, draw the rectangles that can be made from exactly 1 square.

The number 1 has exactly 1 factor, 1.

So, 1 is neither a prime nor a composite number.

Correct answer : (4)

104.

Is 5 a prime or a composite number?

a. | prime | ||

b. | composite |

To find whether 5 is a prime number or not, draw the rectangles that can be made from exactly 5 squares.

From the figure, 5 = 1 × 5

So, the factors of 5 are 1 and 5.

If a number has exactly two factors, 1 and itself, then the number is called a prime number.

So, 5 is a prime number.

Correct answer : (1)

105.

Is 6 a prime or a composite number?

a. | prime | ||

b. | composite |

A number that has more than two factors is called a composite number.

To find whether 6 is a prime number or not, draw the rectangles that can be made from exactly 6 squares.

The dimensions of the rectangle show that the factors of 6 are 1, 2, 3 and 6.

The number 6 has 4 factors.

6 is a composite number.

Correct answer : (2)

106.

Is 8 a prime or a composite number?

a. | prime | ||

b. | composite |

For this, draw a 1 × 8 rectangle and 2 × 4 rectangle.

The dimensions of the rectangle show that the factors of 8 are 1, 2, 4 and 8.

A number that has more than two factors is called a composite number.

8 has 4 factors.

8 is a composite number.

Correct answer : (2)

107.

Is 10 a prime or a composite number?

a. | prime | ||

b. | composite |

For this, draw a 1 × 10 rectangle and 2 × 5 rectangle.

The dimensions of the rectangle show that the factors of 10 are 1, 2, 5 and 10.

A number that has more than two factors is called a composite number.

10 has 4 factors.

10 is a composite number.

Correct answer : (2)

108.

Is 14 a prime or a composite number?

a. | composite | ||

b. | prime |

The dimensions of the rectangle show that the factors of 14 are 1, 2, 7 and 14.

A number that has more than two factors is called a composite number.

14 has 4 factors.

14 is a composite number.

Correct answer : (1)

109.

Is 16 a prime or a composite number?

a. | composite | ||

b. | prime |

The dimensions of the rectangle show that the factors of 16 are 1, 2, 4, 8 and 16.

A number that has more than two factors is called a composite number.

16 has 5 factors.

16 is a composite number.

Correct answer : (1)

110.

Find the prime factorization of 86 using a factor tree.

a. | 43 × 3 | ||

b. | 42 × 2 | ||

c. | 42 × 3 | ||

d. | 43 × 2 |

The factor tree of 86 is

The circled numbers in the factor tree are the prime factors of 86.

The prime factorization of 86 is 43 × 2.

Correct answer : (4)