i’m too clever by half

The what shape is your mind test is pretty clever at first glance, but there’s a pretty basic trick at work here as far as I can tell. Naturally I feel very cocky about having figured out how it works so quickly, very superior, so I’m not going to share the secret with you. Or maybe I will.

Right. Although you’re asked to choose any two digit number, this is just a smokescreen to make you think that the chances of the crystal ball guessing your selection are much higher than they really are. In reality, once you’ve subtracted the two digits that form your number from the number itself there are only a few possible alternatives.

For instance:

  • 29 – 2 – 9 = 18
  • 28 – 2 – 8 = 18
  • 27 – 2 – 7 = 18

In fact, the only numbers that you can possibly end up with are the following: 9, 18, 27, 36, 45, 54, 63, 72, and 81. You’ll notice if you scroll down the list that each of these numbers has the same symbol, so of course the crystal ball gets it right. To conceal this fact, after each click on the crystal ball (or if you just refresh the page) the list is rebuilt to provide a new symbol for all the multiples of nine, so that if you do the test again you’ll get a different, but still correct result. The designer could also use cookies to ensure that you don’t get the same image reappearing. Clever, and yet very simple. And I’m such an unbearable smartass.


  1. This irritatingly got me thinking it was magic or something. Then I realised it was just my stupidity and I was more than a little annoyed.

  2. Don’t be annoyed at the fact you were “tricked”. I am an amateur magician and this actual trick is used as a professional standard by “mind readers” and “psychics” a LOT!

    I put it on the web, because it was easy to transfer… I will be putting more magic online soonish. Most of the rest shouldn’t be so easy to figure out by the smart people :)

  3. no shit, sherlock!

  4. I find it awesome~yet curious that math seems to explain everything. Planetary motion, geometry, literally there is an equation or formula for everything~we just haven’t found them all yet!!

  5. Very fun! One ‘puter online trick that I chose to share with everyone because of it’s ingenuity. But, right, if you notice that the symbols change everytime you ‘try again’, there’s the key. Excellent job, great trick, and lots of fun!

  6. The fun, of course, lies in figuring out how supposedly mysterious stuff like this works, not in being amazed by it. But don’t you mean “…the chances of the crystal ball guessing your selection are LOWER than they are?” Seems to me if you think the chances are high to begin with there is little reason to see if it works or not. From one smartass to another.