We know that a rational number is a number that can be written in the form of 
where p, q 
Z and q ≠ 0. The numbers 25, 3.765, 4.5, etc., are rational numbers. can be reduced to the form where p, q Z, and q ≠ 0 because 
Examples of rational numbers:
i) 0.26= is a rational number.
ii) 3.6666… is a recurring decimal, it is a rational number.
iii) 5.333…is a rational number.
iv) 0.142857142857… is a rational number.
What is Irrational Numbers:-
Irrational numbers are those numbers which cannot be put into the form of where p, q Z and q ≠ 0. The numbers 
are irrational numbers.
Examples of Irrational numbers:
v) 0.0100100010100000001 … is a non-terminating, non-periodic decimal, so it is an irrational number.
vi) 287.12116283873112373573 … is also an irrational number.
vii) 1.4142135 … is an irrational number.
viii) 7.3205080 … is an irrational number.
ix) 1.709975947 … is an irrational number
. x) 3.141592654… is an important irrational number called it (Pi) which denotes the constant ratio of the circumference of any circle to the length of its diameter i.e.,
An approximate value of 
is 
,a better approximation is 
and a still better approximation is 3.14159. The value of is correct to upto 5 lac decimal places has been determined with the help of computer.