A life without numbers is difficult. Numbers have influenced our daily routine in such a way that almost everything we handle depends on numbers. The mobile numbers, time, money, dates, years and so on. Numbers can be of different types, such as integers, natural numbers, whole numbers, odd or even numbers, prime numbers, composite numbers, rational numbers etc.

### EVEN AND ODD NUMBERS:

Integers are a set of numbers which do not have fractional part, they can be positive, negative or zero.

Integers which are divisible by 2 are known as **even numbers**. In other words, numbers whose unit place is 0, 2,4,6,8 are divisible by 2 and such numbers are even numbers.

In contrast, to even numbers, integers which are not divisible by 2 are known as odd numbers. They have 1, 3,5,7,9 at their unit place.

**General Representation of Odd and Even numbers:**

In general format, every Even number can be written in the form of **(2n), **whereas, every odd number can be written in the form of

**(2n-1).**

where, n is a natural number.

*Example of even numbers:*

*Example of even numbers:*

-16, -8, 2, 56, 200

*Example of odd numbers:*

*Example of odd numbers:*

-59, -17, -5, 3, 53, 1, 555,-659

### PRIME AND COMPOSITE NUMBERS:

** **A natural number which has exactly two factors, i.e. 1 and the number itself, is a **prime number**. In simple words, if a number is only divisible by 1 and itself ,then it is a prime number. Every prime number is an odd number except the number 2.

**For example: **

2, 3, 5, 7, 11, 19, 37, 41, 313, 241 etc.

Every non-prime number is a composite number. **Composite numbers** are those natural numbers which have more than two factors. Such numbers are divisible by other numbers as well.

**For example: **

4, 6, 8, 10, 12, 14, 500, 6000 etc.

Some facts about prime numbers and composite numbers are:

- 1 is neither prime nor composite.
- The only even number which is a prime is 2. It is the smallest prime number.