1. Which of the following numbers is not a factor of 68?
2. Which of tfie following numbers is not a factor of 36?
3. Which of the following numbers is not a factor of 24?
4. Which of the following numbers is not a factor of 15?
5. Which of the following number is not a factor of 21?
6. Which of the following number is not a multiple of 27?
7. Which of the following numbers is not a factor of 12?
8. Which of the following numbers is not a factor of 20?
9. Which of the following number is not a factor of 18?
10. Which of the following number is not a multiple of 6?