We know that,
A rational number is a number that is of the form of pq, where p and q are integers and q≠0 . Also p is called the numerator and q is called the denominator.
∴ we have,
Largest number of two digits =99.
Smallest number of four digits =1000.
Numerator = 99 and Denominator =1000.
∴ Rational number =991000
Hence, required number is 991000.