Skills Handbook

Prime Numbers and Composite Numbers

A prime number is a whole number greater than 1 that has exactly two factors, the number 1 and itself.

A composite number is a number that has more than two factors. The number 1 is neither prime nor composite.

You can use a factor tree to find the prime factors of a number. When all the factors are prime numbers, it is called the prime factorization of the number.

Exercises

Is each number prime or composite?

1. 9
2. 16
3. 34
4. 61
5. 7
6. 13
7. 12
8. 40
9. 57
10. 64
11. 120
12. 700

List all the factors of each number.

13. 46
14. 32
15. 11
16. 65
17. 27
18. 29

Use a factor tree to write the prime factorization of each number.

19. 18
20. 20
21. 27
22. 54
23. 64
24. 96

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