problem with a reverse iterator

In the example below, possible_number is a string of one or more 
digit(s). For example, it may be 4 or 4444. However, when I attempt to 
perform the times 2 calculation, the ASCII value of 4 (which is 52) is 
used instead of 4 itself. I need to be able to easily reverse the order 
of the digits and to only perform this calculation on even positioned 
digits... that's why I'm using string instead of int. Any suggestions on 
how to make 4*2 = 8 I've tried atoi() type casting, etc. I'm stuck. 
Still learning c++.

Thanks for any help!

   int position = 0;

   string::reverse_iterator rit;
   for (rit=possible_number.rbegin(); rit < possible_number.rend(); rit++)
       {
       if (position % 2 == 0)
             {
             // Here's the problem *rit * 2 = 104, not 8
             cout << position << *rit * 2 << endl;
             position++;
             }
       }