With the code provided in your post, you can do what you have done without the fstream. Here let me revise it for you.
Code:
#include <iostream.h> 
#include <stdio.h> 

/*void*/ int main() //do not use void.  Read the FAQ on why
{ 
     int Amt; //total numbers to loop
     int i=0;  //starting point
     char str[50]; //an array

     { 
          cout<<"Welcome to the math program.\n"; 
          cout<<"How may numbers do you want to use?"; 
          cin>>Amt; //user input for loop count
     } 

     while(i<Amt) 
     { 
          i++; 
          cout<<"adding 1 to "<<i<<endl;
     } 
}