Prime and 

Composite Numbers

prime

composite

composite

Prime Numbers

What is a prime number?

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

Example: The factors of 2 are 1 and 2. This makes 2 a prime number.

2

1 2x

Why is 12 not a prime number?

The number 12 is not a prime number because it has more factors then 1 and itself.

3

12

6 2

2

x

x

   2   1 x 2

121 x 122 x 63 x 4

What is a composite number?

A composite number is a number that can be broken down into two or more factors.

Example: factors of 16 = 1, 2, 4, 8, 16. 16 is a composite number.

What are composite numbers between 1 and 30?

Compute the prime factorization using stair

steps.

16

First, make a small list of prime numbers for reference..

2 x 2 x 2 x 2 = 24Prime Factorization

Second, build the steps by dividing into 16 using only prime numbers as divisors.

Third, write the equation.

Compute the prime factorization using stair

steps.

50

First, make a small list of prime numbers for reference..

2 x 5 x 5 = 2 x 52Prime Factorization

Second, build the steps by dividing into 50 using only prime numbers as divisors.

Third, write the equation.

Compute the prime factorization using stair

steps.

78

First, make a small list of prime numbers for reference..

Prime Factorization

Second, build the steps by dividing into 315 using only prime numbers as divisors.

Third, write the equation.

2X3X13

Use the division method to find the prime factorization.

27 60     100

Which of the following numbers are prime numbers?

1

A 51

B 7

C 29

D 9

Multiple answer

Which of the following numbers are composite numbers?

2

A 8

B 23

C 36

D 41

Multiple answer

3 Which of the following numbers are prime factors of 45?

A 2, 2, 7

B 3, 3, 5

C 3, 3, 7

D 5, 5, 7

Multiple choice

4 How many prime numbers are there between 1 and 25?

A 9

B 12

C 14

D 15

Multiple choice

Fill in the blanks with the correct word.

1.  A _________________________ number has exactly 

     2 factors, ______________ and itself.

2.  A composite _________________________ has 

     ______________ than two factors.

3.  A factor is a number that _______________________ into

     a whole number _______________ leaving a remainder.

Storage BoxPrime Numbers

1254

77

11

2

1931

99

100

3

17