void rational::print (int);

The default value for floating-point precision is 6. For example, the number 1234.5678 prints as 1234.57. To change the way this value prints, you could use the ios_base member function:

class ios_base{
public:
....
streamsize precision (streamsize n); 
};

A call of precision() affects all floating-point I/O operations until the next call of precision().
For example:

cout.precision(8);
cout << 8765.4321 << ' ' << 9876.54321 << ' '
  << 98765  << endl;
cout.precision(4);
cout << 8765.4321 << ' ' << 9876.54321 << ' '
  << 98765  << endl;

Write an overloaded print() function that calculates the decimal equivalent of the rational number and then prints the decimal equivalent with the precision specified by the function's integer argument.
Using the hint given above, set the output precision to be equal to number of digits up to the decimal point plus the number of desired decimal places of precision.