1. Which of the following numbers are prime numbers? Select ALL that apply.
Answer: B,E
23 and 29 are prime numbers.
Both 23 and 29 meet the criteria for prime numbers, as they have no divisors other than 1 and themselves.
A) 21
21 is not a prime number because it can be divided evenly by 1, 3, 7, and 21. Since it has divisors other than itself and 1, it does not meet the definition of a prime number.
B) 23
23 is a prime number because it can only be divided evenly by 1 and 23. It has no other divisors, confirming its status as a prime number.
C) 25
25 is not a prime number, as it can be divided evenly by 1, 5, and 25. The presence of the divisor 5 means it does not satisfy the conditions for being a prime number.
D) 27
27 is also not a prime number because it can be divided evenly by 1, 3, 9, and 27. Its divisibility by numbers other than 1 and itself disqualifies it from being a prime number.
E) 29
29 is a prime number since it can only be divided evenly by 1 and 29. It has no other divisors, which confirms its classification as a prime number.
Conclusion
The correct answers, 23 and 29, are both prime numbers as they have no divisors other than 1 and themselves. In contrast, 21, 25, and 27 all have additional divisors, making them non-prime. This distinction is essential in understanding the definition of prime numbers.