Math : Prime and Composite numbers

Prime Numbers

 A prime number is a whole number which has ONLY 2 Factors.

Example

Let us consider a whole number 2
2 = 1*2 = 2*1
Here, 1 and 2 are the only 2 factors for 2.

Now let we check 3
3 = 1*3 = 3*1
Here, 1 and 3 are the only 3 factors for 3.

So the prime numbers are 2,3,5,7,11,13...

Note: Prime numbers which can be divided evenly by 1 and by the number itself.

Composite numbers

 A composite number is a whole number which has more than 2 factors.

Example

4 = 1*4 = 2*2 = 4*1

Here, 1,2,4 are the factors for 4. A whole number 4 has 3 factors. Hence 4 is a composite numbers.

4,6,8,9,10,12... are composite numbers.

ONE

1 is neither a prime nor a composite number.
1 = 1*1
1 has only one factor. Hence 1 is not a prime and not a composite number.