Kaplan Nursing Entrance Practice Exam

Which of the following is a prime number?

1. 30

2. 31

3. 32

4. 33

The correct answer is: 31

A prime number is defined as a natural number greater than 1 that has no positive divisors other than 1 and itself. In this case, 31 is the only number in the list that fits this definition. When assessing 31, it cannot be evenly divided by any other numbers aside from 1 and 31 itself. Thus, it qualifies as a prime number. On the other hand, the numbers 30, 32, and 33 each have multiple divisors, demonstrating that they are not prime. For instance, 30 can be divided by 1, 2, 3, 5, 6, 10, 15, and 30; 32 can be divided by 1, 2, 4, 8, 16, and 32; and 33 can be divided by 1, 3, 11, and 33. All these factors indicate that these numbers have divisors other than 1 and themselves, disqualifying them from being classified as prime.