Prime Numbers are numbers which can only be divided by number 1 and that number itself.
Prime Numbers always have only 2 factors.
They are;
The factors of 2 are number 1 and 2 itself. Therefore 2 is a Prime Number.
The factors of 4 are number 1 , 2 and 4 itself. 4 has three factors.
Therefore 4 is not a ‘Prime Number’, it is a ‘Composite Number’.
Number | Factors |
1 | 1 |
2 | 1 , 2 |
3 | 1 , 3 |
4 | 1 , 2, 4 |
5 | 1 , 5 |
6 | 1 , 2, 3 , 6 |
7 | 1 , 7 |
8 | 1 , 2 , 4 , 8 |
9 | 1 , 2 , 3 , 9 |
10 | 1 , 2 , 5 , 10 |
11 | 1 , 11 |
12 | 1 , 2 , 3 , 4 , 6 , 12 |
13 | 1 , 13 |
14 | 1 , 2 , 7 , 14 |
15 | 1 , 3 , 5 , 15 |
16 | 1 , 2 , 4 , 8 , 16 |
17 | 1 , 17 |
18 | 1 , 2 , 3 , 6 , 9 , 18 |
19 | 1 , 19 |
20 | 1 , 2 , 4 , 5 , 10 , 20 |
You can clearly see in the table, that these numbers have only 2 factors.
They are always;
Therefore such numbers are called ‘Prime Numbers’.
Therefore numbers with more than two factors are called ‘Composite Numbers’.
* 1 has only one factor which is 1. Therefore it is neither Prime nor Composite.