Prime Factorization

Prime Factorization

Prime? Composite?

• Prime numbers are numbers that have only 2 factors (the number itself and 1)

• Composite numbers are made up of more than 2 factors

Write these down!

Multiple Choice

A prime number is...

• a number that has only one factor.
• a number that has at least two factors.
• a number that has more than two factors.
• a number that has only two factors.
  (1 and itself)

Multiple Choice

Composite numbers:

• Are always bigger than prime numbers
• Have more than 2 factors
• Have 2 pairs of factors
• Don't have factors

Multiple Choice

What number is the only even prime number?

• 0
• 2
• 1
• 3

Multiple Choice

Which number is NOT prime?

• 3
• 7
• 17
• 21

Multiple Choice

Which is a prime number?

• 15
• 17
• 21
• 39

Multiple Choice

is 5 prime or composite?

• prime
• composite

Multiple Choice

Is 35 prime or composite?

• prime
• composite

Multiple Choice

Find the prime number.

• 10
• 9
• 7
• 4

Multiple Choice

Which number is prime?

• 9
• 5
• 0
• 1

Multiple Choice

which number below is NOT prime?

• 7
• 9
• 2
• 3

Multiple Choice

Which number below is a prime number?

• 1
• 0
• 2
• 9

Multiple Choice

Find the prime number.

• 0
• 1
• 7
• 4

Multiple Choice

Which list is only composite numbers?

• 1, 3, 4
• 2, 4, 6
• 4, 6, 8
• 5, 6, 8

Multiple Choice

Which list has only prime numbers?

• 2, 3, 4, 5
• 1, 5, 7, 9
• 2, 3, 5, 7
• 2, 4, 6, 8

Multiple Choice

the only factors prime numbers have are:

• 0 and 1
• 0 and itself
• 1 and itself
• 1

Factor Trees

• Factor "trees" are used to help us organize factors into prime or composite

• In this example, prime numbers are written in circles

• Composite Numbers are written in squares

Multiple Select

What two numbers should be written in the circles?

• 3

• 2

• 8

• 5

Multiple Select

What two numbers should be written in the circles?

• 3

• 10

• 12

• 11

Multiple Select

What two numbers should be written in the circles?

• 7

• 2

• 8

• 6

Multiple Choice

What number should be paired with the 6?

(Think! ___ x 6 = 12)

• 7

• 2

• 8

• 6

Multiple Select

What two numbers should be written in the circles below the box with 6?

• 12

• 2

• 6

• 3

Prime Factorization using a Factor Tree

• To write the prime factorization of a number, start with a factor tree.

• Any number in a circle (prime numbers) should be included in the list

• Write the list in order from LEAST to GREATEST

• The prime factorization of 12 is ____ x ____ x ____

Multiple Choice

What number should be paired with the 15?

(Remember, think ____ x 15 = 30)

• 3

• 4

• 2

• 15

Multiple Select

What two numbers are the factors of 15?

• 3

• 6

• 5

• 4

Multiple Choice

Write 78 as a product of its prime factors.

• 2 x 39

• 2 x 3 x 13

• 6 x 13

• 2 x 3 x 3 x 4

Multiple Choice

Write 18 as a product of its prime factors.

• 2 x 9

• 3 x 6

• 2 x 3 x 6

• 2 x 3 x 3

Multiple Choice

Write 52 as a product of its prime factors.

• 2 x 2 x 13

• 2 x 26

• 4 x 13

• 2 x 2 x 3 x 4

Multiple Choice

Write 16 as a product of its prime factors.

• 4 x 4

• 2 x 8

• 2 x 2 x 2 x 2

• 2 x 2 x 2 x 2 x 2

Multiple Choice

What is the prime factorization of 90 ?

• 2 x 3 x 3 x 5

• 2 x 5 x 9

• 2 x 3 x 5

• 3 x 30

Multiple Choice

What is the prime factorization of 66 ?

• 6 x 11

• 2 x 3 x 11

• 2 x 33

• 1 x 66

Multiple Choice

What is the prime factorization of 81 ?

• 3 x 27

• 9 x 9

• 3 x 3 x 9

• 3 x 3 x 3 x 3

Multiple Choice

Create a factor tree and find the prime factorization for 80

• 2⁴⋅5

• 4²⋅5

• 2⋅2⋅2

• 8⋅5⋅2

Multiple Choice

Using a Factor Tree, find the prime factorization of 75.  

• 5² x 3
• 5 x 5 x 3
• 3² x 5
• 15 x 5

Multiple Choice

Which is the prime factorization of 12? 

• 2 x 6
• 2 + 2 + 2 + 2 + 2 + 2 
• 2² x 3
• 1 x 2² x 3