Prime Factorization:

Objective: To identify prime and composite numbers.

To write the prime factorization of numbers

Vocabulary

Prime Number: A number greater than 1 that has only two factors (1 and the number itself)

Examples: 5: because 5 and 1 are its only factors

17: because 17 and 1 are its only factors

Composite Number: A whole number greater than one that has more than two factors.

Examples: 6: because it has four factors 1, 2, 3, 6

9: because it has three factors 1, 3, 9

0 and 1 are neither prime or composite

Prime Factorization: A number written as a product of factors that are all prime numbers.

Factor Tree: A useful tool used to find prime factorization.

Example: Make a factor tree for the number 40

40

5 8

4 2

2 25 2

40

2 20

4 5

2 22 5

40

5 8

4 2

2 25 2

All three factor trees have three 2’s and a 5

The prime factorization of 40 is 523

50

2 25

5 52 2•52

120

1012

4 3 5 2

2 2 3 5 2

23•3•5