Eggheads at the Ruđer Bošković Institute in Zagreb, Croatia, are having some geeky fun with their web forms.
If you want to login to the institute's Quantum Random Bit Generator service, you will be asked the usual questions like your username and password, but then you'll be faced by a mathematical problem that may give you a nighmarish memories of your schooldays doing advanced calculus.
Hmm.. it's a bit more complicated than the typical sort of CAPTCHA used by websites around the world to try to block spam bots and automated systems:
Sometimes, of course, these randomly-generated CAPTCHAs can go very wrong - potentially causing unintended offense to some amusement.
Somehow I don't think the calculus-based CAPTCHA is going to catch on with the general public.