Question

what is rational number ?

Answer 1

A rational number is any number that can be expressed as the quotient or fraction p/q of two integers, with the denominator q not equal to zero.

Answer 2

A rational number is a real number which can be expressed as a ratio of two integers.   Like p / q,  where p and q are positive or negative integers.  q is not zero.

examples:    1 / 9  = 0.1111111...    
               12121212/10000000000
               9,          - 3,                  -4.5 = -9/2 ,