recursive - simple screenshot but detail principle.

the code below demonstates the principle of the'recursive-call' that the programing beginner may be confused with,and each demonstrate was followed by a screenshot:

the first part of the code called in the main:

 String s2 = toBinary2(6, sb);

the actual code:

 static String toBinary2(long n, StringBuilder sb)
     {
         if(n > 0)
         {
             toBinary2(n / 2, sb);
             sb.append(n % 2);
         }
         return sb.toString();
     }

the relevant screenshot:

figure 01 - to binary

the second part of the code called in the main:

 int sum = sum(100000);

the actual code:

 static int sum(int num)
     {
         if(num == 1)
             return 1;
         return num + sum(num - 1);
     }

the correspond screenshot: