4. What is the greatest common factor of 12 and 20? A. 8 B. 6 C. 4 D. 2 5. The greatest common factor of 20 and 30 is ____ A. 30 B. 20 C. 10 D. 5 6. Which is the prime factorization of 36? A.2 x 3 x 2 x 2 B. 2 x 2 x 3 x 3 C. 2 x 2 x 2 x 3 x3 D. 2 x 2 x 2 x 2 x 3 x 3 7. What is the greatest common factor of 9 and 21? A. 3 B. 7 C. 9 D. 12 8. The greatest common factor of 14 and 28 is ____ A. 7 B. 12 C. 14 D. 28 9. What is the least common multiple of 8 and 3? A. 24 B. 12 C. 6 D. 3 10. The LCM of 5 and 6 is _____. A. 60 B. 30 C. 15 D. 5