text: #include <cs50.h>
  #include <stdio.h>
  
  int main(void)
  {
      printf("Please enter a number: ");
      int num = GetInt();
      
      int numCopy = num;
      
      int ans = 1;
      
      while (numCopy > 0)
      {
          ans *= numCopy;
          numCopy--;
      }
      
      printf("%d! = %d\n", num, ans);
  }