

1. 
Which of the following numbers is composite? 


A. 
9 
B. 
31 


C. 
1 
D. 
23 


Hint 


2. 
What are the prime factors of 400? 


A. 
2, 4, 5 
B. 
2, 200 


C. 
4, 10, 10 
D. 
2, 5 


Hint 


3. 
What are the prime factors of 810? 


A. 
3, 5 
B. 
3, 4, 5 


C. 
2, 3, 5 
D. 
2, 5, 9 


Hint 


4. 
Write the prime factorization of 810. 


A. 
2 × 5 × 9^{2} 
B. 
2 × 3^{4} × 5 


C. 
2 ×3 × 5 
D. 
3^{2} × 4 × 5 


Hint 


5. 
Factor 20ef. 


A. 
2^{2} · e · f 
B. 
4 · 5 · e · f 


C. 
2 · 2 · 5 · e · f 
D. 
2 · 10 · e · f 


Hint 


