C Program Calculation of Perfect Numbers

Perfect numbers are positive integers which have the special property that the sum of all their factors equals the number itself, e.g., 6 = 1+2+3. The C program finds and prints out all perfect numbers less than 1000.

#include <stdio.h> 
 #include <stdlib.h> 
 #define MAX 1000 
 int main() 
 { 
      long n, sum, j ,k, half; 
      clrscr(); 
      printf("\n PERFECT NUMBERS\n"); 
              for(j=1;j<MAX;j++) 
               { 
                  half= (j+1)/2; 
                  sum = 0; 
                   for(k=1;k<=half; k++) 
                   { 
                              if(j%k==0) sum+= k; 
                   } 
                           if(sum==j) 
                           { 
                              printf("\r %7ld is a perfect number.\n", j); 
                           } 
               } 
      return 0; 
 }