PRIME AND COMPOSITE NUMBERS WORKSHEET

Question 1 :

How many prime prime numbers are between 11 and 60?

Question 2 :

Find the number of distinct prime factors of the smallest 4 digit number.

Question 3 :

Find the sum of distinct prime factors of 30. 

Question 4 :

Write the smallest and the biggest three digit composite number.

Question 5 :

Write the smallest and the biggest two digit prime number.

Question 6 :

The sum of any three odd natural numbers is odd. Justify this statement with an example.

Question 7 :

The digits of the prime number 13 can be reversed to get another prime number 31. Find if any such pairs exist up to 100.

Question 8 :

Your friend says that every odd number is prime. Give an example to prove him/her wrong.

Question 9 :

Each of the composite numbers has at least three factors. Justify this statement with an example.

Question 10 :

I am a two digit prime number and the sum of my digits is 10. I am also one of the factors of 57. Who am I?

Question 11 :

I am a two digit composite number less than 30. If 2, 3, 4, 6 and 8 are my factors, who am I?

Question 12 :

How many even prime numbers are there ?

Question 13 :

Explain why 6 is a perfect number. 

Question 14 :

Write 2 two digit composite numbers which are evenly divisibly by 5, and 7.  

Question 15 :

Generate a three digit composite number with different digits that is evenly divisible by 11.   

Answers

1. Answer :

12

2. Answer :

2

3. Answer :

10

4. Answer :

smallest ----> 100; biggest ----> 999

5. Answer :

smallest ----> 11; biggest ----> 97

6. Answer :

True. 3 + 7 + 9 = 19 is odd

7. Answer :

(17, 71),(37,73) & (79,97)

8. Answer :

False. 9 is odd number but not prime

9. Answer :

True. The composite number 4 has 3 factors namely 1, 2, and 4.

10. Answer :

19

11. Answer :

24

12. Answer :

Only one. That is 2. 

13. Answer :

6 is a perfect number, since adding the factors of 6 (other than 6), namely 1, 2 and 3 gives the given  number 6. That is, 1 + 2 + 3 = 6 is the given number.

14. Answer :

35 and 70

15. Answer :

132

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