•  Prime & Composite Numbers

     

    3 and 7 are both prime numbers. 

    7 can only be divided evenly by 1 or itself without a remainder, so it is a prime number

    1 x 7  or  7 x 1

    3 can only be divided evenly by 1 or itself without a remainder, so it is a prime number

    1 x 3  or 3 x 1

     

    6 is a composite number.

    6 can be divided evenly by 1, 2, 3 and 6 so it is NOT a prime number

    1 x 6   6 x 1   2 x 3   3 x 2

     

    Click here to watch a helpful video.

    Click here to practice with prime & composite numbers online.

     

    Factor sets and can also be used to help determine if a number is prime or composite.

    Factor sets are simply the sets of multiplication facts that can be used to create a particular number.  These can then be used to determine if a number is prime or composite.

     

    Example:

    The multiplication facts for 12 are

    1 x 12     12 x 1     2 x 6     6 x 2   3 x 4    4 x 3

     

    These factors can then be organized into a list or a T-chart.  Each factor will be listed only once.

    List:  1, 2, 3, 4, 6, and 12

     T-chart: 

         Factors of 12

    A number is composite if it can be made using factor sets other than one and itself, so 12 is a composite number.

     

    Here are some more examples of factor sets listed in T-charts.

    Factor Sets