# Mind Reading Java Game - How does this work?! **URL:** \ **Category:** Factual Questions\ **Created:** [May 30, 2006, 4:08pm UTC](https://boards.straightdope.com/t/mind-reading-java-game-how-does-this-work/358747 "2006-05-30T16:08:05Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![shelbo](https://avatars.discourse-cdn.com/v4/letter/s/3d9bf3/32.png) [@shelbo](https://boards.straightdope.com/u/shelbo)\ **Post date:** [May 30, 2006, 4:08pm UTC](https://boards.straightdope.com/t/mind-reading-java-game-how-does-this-work/358747/1 "2006-05-30T16:08:05Z")
[How do it know?](http://www.gujaratplus.com/cball/middle.html) ---
**Author:** ![shelbo](https://avatars.discourse-cdn.com/v4/letter/s/3d9bf3/32.png) [@shelbo](https://boards.straightdope.com/u/shelbo)\ **Post date:** [May 30, 2006, 4:15pm UTC](https://boards.straightdope.com/t/mind-reading-java-game-how-does-this-work/358747/2 "2006-05-30T16:15:36Z")
OK, I figured it out. Cute. ---
**Author:** ![jawdirk](https://avatars.discourse-cdn.com/v4/letter/j/df705f/32.png) [@jawdirk](https://boards.straightdope.com/u/jawdirk)\ **Post date:** [May 30, 2006, 4:33pm UTC](https://boards.straightdope.com/t/mind-reading-java-game-how-does-this-work/358747/3 "2006-05-30T16:33:05Z")
Let the first digit of your number be x, and the second digit y. Then after you do the computation you will get 10x+y-x-y=9x. The applet puts the same symbol next to all the multiples of 9 so you are assured of picking it. ---
**Author:** ![Crotalus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/crotalus/32/41_2.png) [@Crotalus](https://boards.straightdope.com/u/Crotalus)\ **Post date:** [May 30, 2006, 4:36pm UTC](https://boards.straightdope.com/t/mind-reading-java-game-how-does-this-work/358747/4 "2006-05-30T16:36:04Z")
> [@shelbo](#): > > OK, I figured it out. Cute. Good for you! So did I. Let’s not tell anyone. ---
**Author:** ![MrSquishy](https://avatars.discourse-cdn.com/v4/letter/m/b9e5f3/32.png) [@MrSquishy](https://boards.straightdope.com/u/MrSquishy)\ **Post date:** [May 30, 2006, 6:38pm UTC](https://boards.straightdope.com/t/mind-reading-java-game-how-does-this-work/358747/5 "2006-05-30T18:38:46Z")
Nerdy Nitpick: It’s Flash, not Java. An easy way to tell? It’s called the Flash Mind Reader. 🙂 ---
**Author:** ![control-z](https://avatars.discourse-cdn.com/v4/letter/c/eada6e/32.png) [@control-z](https://boards.straightdope.com/u/control-z)\ **Post date:** [May 30, 2006, 6:40pm UTC](https://boards.straightdope.com/t/mind-reading-java-game-how-does-this-work/358747/6 "2006-05-30T18:40:28Z")
That’s cool. Once again it shows you not to assume anything. ---
**Author:** ![WOOKINPANUB](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wookinpanub/32/132_2.png) [@WOOKINPANUB](https://boards.straightdope.com/u/WOOKINPANUB)\ **Post date:** [May 30, 2006, 7:08pm UTC](https://boards.straightdope.com/t/mind-reading-java-game-how-does-this-work/358747/7 "2006-05-30T19:08:51Z")
Sorry to be such a chowderhead, but can someone explain it to me, reeeaal sloooowwww like. I’m not the swifted gazelle on the plain when it comes to that there numberology stuff. ---
**Author:** ![Giles](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/giles/32/60_2.png) [@Giles](https://boards.straightdope.com/u/Giles)\ **Post date:** [May 30, 2006, 7:18pm UTC](https://boards.straightdope.com/t/mind-reading-java-game-how-does-this-work/358747/8 "2006-05-30T19:18:59Z")
> [@WOOKINPANUB](#): > > Sorry to be such a chowderhead, but can someone explain it to me, reeeaal sloooowwww like. I’m not the swifted gazelle on the plain when it comes to that there numberology stuff. Start with a two digit number AB. That 10 times A, plus B. Take A + B away from it, and you get 9 times A. The only possible answers are the numbers from 9 times 1, through to 9 times 9, i.e. 9, 18, 27, …, 81. These all have the same symbol next to them, ---
**Author:** ![control-z](https://avatars.discourse-cdn.com/v4/letter/c/eada6e/32.png) [@control-z](https://boards.straightdope.com/u/control-z)\ **Post date:** [May 30, 2006, 7:28pm UTC](https://boards.straightdope.com/t/mind-reading-java-game-how-does-this-work/358747/9 "2006-05-30T19:28:05Z")
> [@Giles](#): > > Start with a two digit number AB. That 10 times A, plus B. Take A + B away from it, and you get 9 times A. The only possible answers are the numbers from 9 times 1, through to 9 times 9, i.e. 9, 18, 27, …, 81. These all have the same symbol next to them, Yes, the answer will always be a multiple of 9. The game encourages you to try it again. So you try another 2-digit number. It has a different symbol next to it than the last number you tried. And it figures out your symbol again!! The trick is, all the symbols beside powers of 9 are the same, and it puts a different symbol next to the powers of 9 each time you try the game! That’s what makes it seem like it’s reading your mind.