# Prime and Composite Numbers

## Prime Numbers

The mathematical definition of a prime number is a number that has exactly two factors (no more or no less). Commonly though people think of prime numbers as being those that can only be divided exactly by 1 and by the number itself.

The number 7 is not exactly divisible by any
number other than 1 and 7

It has two factors only; 1 and 7

Therefore, 7 is a prime number.

In other words, **prime numbers have only 2 factors. **

The first five prime numbers are; 2 , 3, 5 , 7 , 11

Click
here for a chart listing prime numbers up to 251

#### Is 1 a Prime Number?

The number 1 has only one factor so **1 is not a prime number.**

## Composite Numbers

A natural number that has more than two factors is called a composite
number. In other words, a composite number has factors in addition
to one and itself.

- All even numbers are divisible by two and so all even numbers greater
than two are composite numbers.
- All numbers that end in five are divisible by five. Therefore all
numbers that end with five and are greater than five are composite
numbers.
- The numbers 0 and 1 are neither prime nor composite.
- If any whole number greater than 1 is not a prime number, then
it is a composite number.

## Prime or Composite?

Number |
Factors (or can be exactly divided by) |
Composite or Prime? |

2 |
1 , 2 |
Prime |

3 |
1 , 3 |
Prime |

4 |
1 , 2 , 4 |
Composite |

5 |
1 , 5 |
Prime |

6 |
1 , 2 , 3 , 6 |
Composite |

7 |
1 , 7 |
Prime |

8 |
1, 2 , 4 , 8 |
Composite |

9 |
1, 3 , 9 |
Composite |

10 |
1, 2 , 5 , 10 |
Composite |

11 |
1, 11 |
Prime |

12 |
1 , 2 , 3 , 6 , 12 |
Composite |

13 |
1, 13 |
Prime |

14 |
1, 2 , 7 , 14 |
Composite |

15 |
1, 3 , 5 , 15 |
Composite |

Try our fun
Prime or Composite math game and also have a go at the Factors
- Prime and Composite Numbers worksheets below.

## Prime/ Composite Worksheets