text: #include <stdio.h>
  
  int factorial(unsigned int number) {
      int sum = number;
  
      if (sum > 1) {
          sum *= factorial(number - 1);
      }
  
      return sum;
  }
  
  void main() {
      /* testing code */
      printf("1! = %i\n", factorial(1));
      printf("3! = %i\n", factorial(3));
      printf("5! = %i\n", factorial(5));
  }