/* determine factorial of a number */

x = 1 /* x will be incremented in loop */
i = 1

say "Do you want to know the factorial of a number?"
say "Then enter your number:"

parse pull num /* wait for input */

if num < 0 then
    do
        say "There are no factorials for negative numbers!"
        exit /* exit programm if num < 0 */
    end
else
    do until x > num
        i = i * x /* multiply i with current x */
        x = x + 1 /* increment x until x = num */
    end

say num ||"! is" i"."