# Types of Number

## Natural Number

Any number that matches the numbers those starts from $$1, 2, 3, 4, ….$$ is called a Natural Number or Counting number.

Example

$$4, 9 , 11, 35, 99, 500$$ or $$9876$$ are natural numbers.

## Whole Number

Any number that matches the numbers those starts from $$0, 1, 2, 3, 4, ….$$ is called a Whole Number.

Example

$$0, 2, 14 , 23, 48, 172, 623$$ or $$1245$$ are whole numbers.

## Integers

All natural numbers and negative of natural numbers including zero are called Integers.

Example

$$-65, -12, -5, 0, 56, 89$$ or $$354$$ are Integers.

Note

Zero is neither a negative number nor positive number. It is a neutral number.

## Rational Numbers

The numbers each of which can be expressed in the form of $$\frac{p}{q}$$, where p and q are integers and q is not equal to zero, are called Rational Numbers. Besides, the rational numbers are also non terminating and repeating numbers.

Example

$$\frac{2}{5}$$, $$\frac{1}{3}$$, $$\frac{8}{9}$$, $$\frac{3}{10}$$ etc.

## Irrational Numbers

The numbers which are not rational are called irrational numbers. Besides, irrational numbers are also non terminating and non repeating numbers.

Example

$$\sqrt 2$$, $$\sqrt 5$$ etc.

## Real Numbers

Set of rational numbers and irrational numbers is called Real Numbers.

Example

$$\sqrt 7$$, $$\frac{1}{8}$$, $$\frac{3}{10}$$ etc.

## Prime Number

Any Natural number greater than $$1$$, which is divisible by $$1$$ and only by itself is called Prime Number.

Example

$$2$$, $$3$$, $$5$$, $$7$$, $$11$$ etc.

Note

$$2$$ is the smallest Prime Number.

## Composite Number

Any Natural number, which is greater than $$1$$ and is not a Prime Number is called a Composite Number.

Example

$$4$$, $$6$$, $$8$$, $$9$$, $$10$$ etc.

Note

$$1$$ is neither a Prime Number nor Composite Number.

## Coprimes

Two numbers are called to be coprime or co-prime if they have only $$1$$ as common factor.

Example

$$(2,3)$$, $$(14,15)$$, $$(8,13)$$ etc.

## Twin Primes

Two numbers are called Twin Primes if they differ by 2 only or we can say that there is only one composite number between them.

Example

$$(3,5)$$, $$(29,31)$$, $$(71,73)$$ etc.

## Prime Triplets

A set of three consecutive Prime Numbers if they differ by 2, is called a Prime Triplet.

Example

$$(3,5,7)$$ etc.