Lowpoint-Washburn Public School District 21    508 East Walnut Street    Washburn, IL  61570  Phone: 309.248.7522  Fax: 309.248.7518

Composite Numbers  

A “Composite” number is a number that can be divided by any other number besides itself.

 

Example

Which of these numbers are composite?   27, 45, 41, 51

27 is composite because it can be divided by 3 or 9.

45 is composite because it can be divided by 3, 5, 9, or 15.

41 is not composite because it can only be divided by one or itself so it is a prime number!

51 is composite because it can be divided by 3 or 17. 

 

Students can use a 100 chart and circle all of the prime numbers and put an X through all of the composite numbers.  This will save them time instead of having to figure each number out! 

 

Factors of Composite numbers

Since a composite number is a number that is divisible by other numbers, factors of a composite number are the numbers that you can multiply together to get that number.

 

Example

Choose the correct statement.

7 is a factor of 28.  This is true because 7x4 =28

54 is a factor of 10.  This is not correct because you can not take 54 x ? = 10

28 is a factor of 7.  This is not true because you can not take 28 x ? =7

 

Example

 List all of the factors of 48

A. 1, 2, 3, 4, 6, 8, 12, 16, 24, 48                             B. 1, 2, 23, 46, 48

C. 1, 2, 3, 4, 5, 6, 8, 12, 15, 22, 24, 48          D. 1, 2, 3, 6, 11, 22, 33, 66

 

First make a list of all the factors of 48.

1x48, 2x24, 3x16, 4x12, 6x8.  List each number factor only once. Then put the numbers in numerical order.  So the correct answer would be

A. 1, 2, 3, 4, 6, 8, 12, 16, 24, 48