Theory:

If we want to find more number of rational numbers between two numbers, then we should find the multiples of the rational numbers given.
 
For example, if we want to find more number of rational numbers between  35and45. We should write the multiple of the rational numbers, that is, 35canbewrittenas3050and45canbewrittenas4050
 
This can be better understood by representing in a number line,
 
ni.jpg
 
We can find even more number of rational numbers between 35and45 by writing the multiple of a rational number as 300500and400500. Now, there are \(100\) rational numbers present between 35and45.
 
From, this we can understand that an infinite (or) an uncountable number of rational numbers are present between any two rational numbers.