﻿ Prime and Composite Numbers Worksheet - Page 3 | Problems & Solutions

Prime and Composite Numbers Worksheet - Page 3

Prime and Composite Numbers Worksheet
• Page 3
21.
_____ is the only even and the smallest prime number.
 a. 1 b. 3 c. 2

Solution:

2 is the only even and the smallest prime number.

22.
Every _________ number can be written as the product of prime numbers.
 a. Whole b. Prime c. Composite d. None of the above

Solution:

Every composite number can be written as the product of prime numbers.

23.
Since 1 has only _____ factor(s), it is neither prime nor composite.
 a. 4 b. 2 c. 1

Solution:

Since 1 has only 1 factor, it is neither prime nor composite.

24.
The greatest prime number less than 100 is ____.
 a. 99 b. 91 c. 97 d. 95

Solution:

The greatest prime number less than 100 is 97.

25.
Every ________ number greater than 2 is either prime or composite.
 a. Real b. Complex c. Whole d. Natural

Solution:

Every whole number greater than 2 is either prime or composite.

26.
Which of the following is not a prime number?
 a. 2 b. 17 c. 11 d. 12

Solution:

A prime number has exactly two factors, 1 and itself.

Factors of 11: 1 and 11
Factors of 19: 1 and 19
Factors of 17: 1 and 17
Factors of 12: 1, 2, 3, 4, 6, 12

The number 12 has more than 2 factors.

So, the number 12 is not a prime number.

27.
Which of the following is not a composite number?
 a. 12 b. 17 c. 22 d. 26

Solution:

A composite number has more than two factors.

Factors of 26: 1, 2, 13 and 26
Factors of 22: 1, 2, 11 and 22
Factors of 17: 1 and 17
Factors of 12: 1, 2, 3, 4, 6, 12

The number 17 has exactly 2 factors, 1 and 17.

So, the number 17 is not a composite number.

28.
Which of the following arrays shows a prime number?

 a. Figure 3 b. Figure 1 c. Figure 4 d. Figure 2

Solution:

A prime number is represented using exactly one rectangular array.

In the given figure, Figure 3 shows exactly one rectangular array.

So, the array represented in Figure 3 shows a prime number.