Prime and Composite Numbers

This lesson is on prime and composite numbers.

First, you will copy the worksheet I have included in this lesson. Then, you will explain the difference between prime and composite numbers.

A prime number only has factors of 1 and the number.

Example: 7 = 1 and 7. 1 x 7 = 7

The factors of 7 are 1 and 7.

Therefore, 7 is a prime number.

A composite number has more than two factors.

Example: 9 is a composite number.

9 x 1 = 9

3 x 3 = 9

The factors of 9 = 1, 3, 9.

After you have gone over some examples of prime and composite numbers, then you can pass out the worksheet. Worksheet: Prime and Composite Numbers.

Directions: Write Prime or Composite after each number.

1. 16 =

2. 23 =

3. 35 =

4. 41 =

5. 47 =

6. 100 =

7. 50 =

8. 45 =

9. 22 =

10. 21 =

11. 2 =

12. 5 =

13. 8 =

14. 54 =

15. 48 =

16. 33 =

17. 19 =

18. 61 =

19. 72 =

20. 75 = Answer Sheet to Prime and Composite Numbers

1. 16 = Composite

2. 23 = Prime

3. 35 = Composite

4. 41 = Prime

5. 47 = Prime

6. 100 = Composite

7. 50 = Composite

8. 45 = Composite

9. 22 = Composite

10. 21 = Composite

11. 2 = Prime

12. 5 = Prime

13. 8 = Composite

14. 54 = Composite

15. 48 = Composite

16. 33 = Composite

17. 19 = Prime

18. 61 = Prime

19. 72 = Composite

20. 75 = Composite

Each question is worth five points.

100 to 90 = A

89 to 80 = B

79 to 70 = C

69 to 60 = D

Below 60 = F