1. Which of these numbers cannot be written as a product of two co-prime integers greater than 1?

2. The sum of all factors of 10 is —

3. Find the least number which when divided by 5, 6 and 8 leaves remainder 2 in each case.

4. If p is a prime number, which of the following is always true?

5. Which of the following numbers is a prime number?

6. Prime factorization of 20 is:

7. Which of the following numbers is divisible by 2?

8. Which number is divisible by 5?

9. Which number is divisible by 3?

10. Which number is divisible by 9?