#include <stdio.h>

main()
{
   int n, nfac;

   printf("\nEnter a number (>= 0): ");
   scanf("%d", &n);
   printf("\n %d! = ", n);
                   /* NOTE: The exclamation mark isn't some form of operator,
                      but will be printed. As no carriage return escape
                      operator is employed at the end of the character string,
                      the next printf statement will carry on exactly where
                      this one left off.                                  */
   nfac = 1;
   while (n > 0)
   {
      nfac *= n;
                   /* The assignment operators beginning with a mathematical
                      symbol and ending with an equals sign mean that the
                      new definition for the variable being redefined is
                      equal to the variable, affected in some way by another
                      variable. The way in which it is affected is determined
                      by the mathematical symbol at the start of the
                      assignment operator, e.g. nfac *= n means
                      nfac = nfac * n.                                    */
      n -= 1;
                   /* Equals n = n - 1. You get the general idea.         */
   }
   printf("%d\n", nfac);
}