Rational Numbers
In order to acquire a strong understand of the basic concepts associated with calculus, you should understand the real number system. Real numbers fall into quite a few different categories including integers, rational numbers and irrational numbers.
A rational number is a real number that can be written as a quotient of two integers, where the integer ( 1 ,2, 3 etc) in the denominator is not zero:
r = 
also, ‘n’ is also a rational number in this case because
Examples of rational numbers
(a) 
example
As you can see, rational numbers can be represented in an infinite amount of different ways, that is, you can keep incrementing the numerator and denominator appropriately to acquire the same result. Any number that is not rational is called irrational, click here to read about irrational numbers.