# Prime and Composite Numbers

Prime numbers are numbers that are divisible by one and itself or we can say that they have exactly two factors. These numbers only appear in the tables of 1 and the number itself. They do not appear in the table of other numbers.

Examples are: 2, 3, 5, 7, 11, and 13…… etc

Composite numbers are numbers that are not only divisible by one and itself but are divisible by other numbers as well or we can say they do not have exactly two factors but more number of factors. These numbers appear in the tables of various other numbers except one and the number itself.

Examples are: 4, 6, 8, 9, 12, 14, 16, and 18 ……….etc.

1 does not fall under the head of prime or composite number hence termed as co-prime number.

How can we find out whether a number is prime or composite?

Check the factors of the given number

There are two possibilities

Here is a list showing all the prime numbers

The numbers that are highlighted are prime numbers and the numbers that are not highlighted are called composite number.

1 is not highlighted but it is not a composite number it is a co-prime number as mentioned earlier.

One important thing to note from the grid of numbers given is that all the prime numbers are odd numbers except 2. That is why 2 is called the only even prime number as all other prime numbers are odd.

Examples of sum more prime numbers:

101, 103, 107, 109, 113, 127, 131, 137, 139, 149

Example:

Find the prime numbers from 50 to 60

 Factors of 50 50 × 1 = 502 × 25 = 505 × 10 = 50 More than 2 factors; composite Factors of 51 51 × 1 = 51 3 × 17 = 51 More than 2 factors; composite Factors of 52 52 × 1 = 52 26 × 2 = 52 13 × 4 = 52 More than 2 factors; composite Factors of 53 53 × 1 = 53 2 factors; Prime Factors of 54 54 × 1=54 2 × 27 = 54 3 × 18 = 54 6 × 9 = 54 More than 2 factors; composite Factors of 55 55 × 1 = 55 11 × 5 = 55 More than 2 factors; composite Factors of 56 56 × 1 = 56 2 × 28 = 56 7 × 8 = 56 4 × 14 = 56 More than 2 factors; composite Factors of 57 57 × 1 = 57 3 × 19 = 57 More than 2 factors; composite Factors of 58 58 × 1 = 58 2 × 29 = 58 More than 2 factors; composite Factors of 59 59 × 1 = 59 2 factors ; Prime Factors of 60 60 × 1 = 606 × 10 = 602 × 30 = 603 × 20 = 604 × 15 = 6012 × 5 = 60 More than 2 factors; composite