# Why are prime numbers different from other numbers in Real number system?

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**Prime numbers are those which have only two Factors. 1 and the number it self.** That is to say no other number can perfectly divide the given prime number. For Example 2,3,5,7,11 .... etc which are prime numbers ... each of these can only be divisible by either 1 or the number itself. On the contrary other numbers i.e Composite numbers have more than two factors. Each of the composite numbers has at least 1 more factor besides 1 and the number itself. For example 4 which has 1,2 and 4 as its factors.

**An exponent is the number of times the base is multiplied by itself.**

Ex 2^3 (2 cubed or 2 raised to power 3) means 2 X 2 X 2 ( 2 multiplied with itself 3 times which is 8. The number that is being multiplied repeatedly is called the base or root or radical where as the number of 'times' it is multiplied is known as the index or power or exponent.

**Difference between a Fraction and a Decimal.**

A Decimal is also a fraction with the denominator being either 10 or the exponents of 10. A fraction on the other hand denotes simply a part of the whole. Decimal fractions is a logical development of the base 10 place value.

Examples of Fractions - 1/2 (half), 2/3 (two thirds) etc

Decimal Fractions - 0.2 = 2/10, 0.05 = 5/100 etc

A natural number p>1 is said to be a prime number if its only factors are 1 and the number itself.

e.g. 2=1.2

3=1.3

5=1.5 etc.

All other numbers other than these prime numbers are called composite numbers. And every composite number can be expressed as a product of prime numbers.

e.g. 4=2.2

6=2.3

8=2.2.2.2

28=2.2.7 etc.