Which one of the following is not a prime number 31 61
- Which one of the following is not a prime number 31 61 71 of 91
- Which one of the following is not a prime number 31 61 91
- Which one of the following is not a prime number * 31 61 71
- Which one of the following is not a prime number
- 91 is a prime number
- Which of the following numbers is a prime number
- Which of the following numbers are prime