In various types of numbers we will learn about even numbers, odd numbers, prime numbers, composite numbers, co-prime numbers and twin prime numbers along with the example:

**Even Numbers**A whole number exactly divisible by 2 is called

*even numbers*.

**For example:**

2, 4, 6, 8, 10, 12, 14, 16..........................are

*even number*.Or a number having 0, 2, 4, 6, 8 at its units place is called an

*even number*.

246, 1894, 5468, 100 are *even number*.

Any two even numbers which differ from one another by 2 are called *consecutive even number*.

**Odd Numbers**

A whole number which is not exactly divisible by 2 is called an *odd number*.

**For example:**

3, 5, 7, 9, 11, 13, 15, are odd number.

Or a number having 1, 3, 5, 7 and 9 at its units place is called an *odd number*.

**Prime Numbers**

Number s which have only two factors namely 1 and the number itself are called *prime numbers*.

**For example:**

2, 3, 5, 7, 11, 19, 37 etc are *prime numbers*.

**Composite Numbers**

Numbers having more than two factors are called as *composite numbers*.

**For example:**

4, 6, 8, 10 etc are *composite numbers*.

**Notes:**

(a) 1 is neither prime nor composite.

(b) 2 is the lowest and the only even prime number.

(c) 9 is the lowest odd composite number.

**Co-prime Numbers**

Two numbers are said to be *co-prime* if they do not have a common factor other than 1 or two numbers whose HCF is 1 called *co-prime numbers*.

*Co-prime numbers needs not be prime numbers.*

**For example:**

(i) 7 and 10 are co-prime.

(ii) 15 and 17 are co-prime.

**Twin Prime Numbers**

*Twin prime numbers* are the two prime numbers whose difference is 2.

**For example:**

(i) 3 and 5

(ii) 17 and 19

(iii) 41 and 43

(iv) 29 and 31

(v) 71 and 73.