Which statement correctly describes why the number 21 is NOT a prime number?

Because its only factors are 1 and 21.

Because it has more than two factors.

Factors Practice — Grade 6 math

1. The number 18 has exactly ___ factors.
2. Which of the following numbers is a prime number?
- A. 9
- B. 13
- C. 15
- D. 1
3. What is the largest factor of 36, not including 36 itself? The answer is ___.
4. Which statement correctly describes why the number 21 is NOT a prime number?
- A. Because it is an odd number.
- B. Because its only factors are 1 and 21.
- C. Because it has more than two factors.
- D. Because it is greater than 10.
5. Which of the following numbers is NOT a factor of 30?
- A. 3
- B. 4
- C. 5
- D. 6
6. Which of the following statements provides the correct definition of a prime number?
- A. Any whole number that is odd.
- B. A number that has more than two factors.
- C. A number with exactly two factors: 1 and itself.
- D. A number that is not divisible by 2.
7. The number 91 is a composite number because it is divisible by a prime number other than 1 or 91. One of these prime factors is ___.
8. The number 1 is not considered a prime number. What is the reason for this?
- A. Because it is an odd number.
- B. Because it is a factor of every other number.
- C. Because it has only one factor.
- D. Because it is the smallest positive whole number.
9. The first six prime numbers are 2, 3, 5, 7, 11, and 13. What are the next three prime numbers after 13?
- A. 15, 17, 19
- B. 17, 19, 21
- C. 17, 19, 23
- D. 14, 15, 16
10. Consider the list of numbers: 2, 15, 23, 39, 41. How many of these numbers are prime? ___