# How Does It Know?!? Please Tell Me! **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [March 29, 2003, 9:12pm UTC](https://boards.straightdope.com/t/how-does-it-know-please-tell-me/165078 "2003-03-29T21:12:59Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![DougAB](https://avatars.discourse-cdn.com/v4/letter/d/e47c2d/32.png) [@DougAB](https://boards.straightdope.com/u/DougAB)\ **Post date:** [March 29, 2003, 9:12pm UTC](https://boards.straightdope.com/t/how-does-it-know-please-tell-me/165078/1 "2003-03-29T21:12:59Z")
[The Internet Mind Reader](http://mr-31238.mr.valuehost.co.uk/assets/Flash/psychic.swf) When I saw this I immediately thought, “How?!?” Then I realized if anyone knew, they’d probably be here. So please, try, and please, explain! ---
**Author:** ![heresiarch](https://avatars.discourse-cdn.com/v4/letter/h/278dde/32.png) [@heresiarch](https://boards.straightdope.com/u/heresiarch)\ **Post date:** [March 29, 2003, 9:18pm UTC](https://boards.straightdope.com/t/how-does-it-know-please-tell-me/165078/2 "2003-03-29T21:18:10Z")
99-18=81 98-17=81 97-16=81 hmmm. Let’s try a couple others 57-12=45 56-11=45 55-10=45 OK, there are only a handful of results possible. And there’ll all multiples of 9. All the multiples of 9 have the same symbol. There you are. ---
**Author:** ![Spit](https://avatars.discourse-cdn.com/v4/letter/s/76d3ee/32.png) [@Spit](https://boards.straightdope.com/u/Spit)\ **Post date:** [March 29, 2003, 10:05pm UTC](https://boards.straightdope.com/t/how-does-it-know-please-tell-me/165078/3 "2003-03-29T22:05:19Z")
Notice also that the symbols change every round, so that it becomes even more mysterious. ---
**Author:** ![DougAB](https://avatars.discourse-cdn.com/v4/letter/d/e47c2d/32.png) [@DougAB](https://boards.straightdope.com/u/DougAB)\ **Post date:** [March 29, 2003, 11:16pm UTC](https://boards.straightdope.com/t/how-does-it-know-please-tell-me/165078/4 "2003-03-29T23:16:44Z")
Also I may just be getting played like a fool, but it has not worked once when I pick a number without going through the addition and subtraction. ---
**Author:** ![MegTheMermaid](https://avatars.discourse-cdn.com/v4/letter/m/6de8d8/32.png) [@MegTheMermaid](https://boards.straightdope.com/u/MegTheMermaid)\ **Post date:** [March 29, 2003, 11:21pm UTC](https://boards.straightdope.com/t/how-does-it-know-please-tell-me/165078/5 "2003-03-29T23:21:27Z")
Holy man. That’s creepy, to say the least. I’m really not sure how that works. But it’s mind boggling. ---
**Author:** ![samarm](https://avatars.discourse-cdn.com/v4/letter/s/4da419/32.png) [@samarm](https://boards.straightdope.com/u/samarm)\ **Post date:** [March 29, 2003, 11:24pm UTC](https://boards.straightdope.com/t/how-does-it-know-please-tell-me/165078/6 "2003-03-29T23:24:54Z")
**heresiarch** is on the right track. For a full explanation, see this thread: [http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=165603&highlight=multiples](http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=165603&highlight=multiples) ---
**Author:** ![NameAlreadyTaken](https://avatars.discourse-cdn.com/v4/letter/n/97f17d/32.png) [@NameAlreadyTaken](https://boards.straightdope.com/u/NameAlreadyTaken)\ **Post date:** [March 29, 2003, 11:25pm UTC](https://boards.straightdope.com/t/how-does-it-know-please-tell-me/165078/7 "2003-03-29T23:25:38Z")
**DougAB** , it won’t work unless you specifically follow the directions because the symbols change on every page load. That is, if you pick your “start symbol”, click “continue” and then hit the back arrow to see if it was right, you won’t get a valid result because the symbols on the page change, as pointed out by **Spit**. So if you play any games with it, the way you would with a card trick or a human, the mind reader breaks. You have to do the addition and subtraction and pick the resulting symbol before continuing. You can’t go backwards becuase the symbols change to make you think it’s a random (mysterious and powerful) process. **Heresiarch** hit it on the head. Every possible addition/subtraction result on any give page is linked to the same symbol. In order to make it less obvious, the exact symbols change every time you load the page. Which leads to the confusion. You can’t use the back button to verify results because that triggers the symbol shuffling (to prevent you from really looking at the layout and noticing the math!). ---
**Author:** ![NameAlreadyTaken](https://avatars.discourse-cdn.com/v4/letter/n/97f17d/32.png) [@NameAlreadyTaken](https://boards.straightdope.com/u/NameAlreadyTaken)\ **Post date:** [March 29, 2003, 11:27pm UTC](https://boards.straightdope.com/t/how-does-it-know-please-tell-me/165078/8 "2003-03-29T23:27:27Z")
I really have to start looking at the SMDB archives. This is twice that someone has pointed out a pre-existing thread that is a better/more complete version of what I post. Sucks to be new at this. ---
**Author:** ![DougAB](https://avatars.discourse-cdn.com/v4/letter/d/e47c2d/32.png) [@DougAB](https://boards.straightdope.com/u/DougAB)\ **Post date:** [March 29, 2003, 11:30pm UTC](https://boards.straightdope.com/t/how-does-it-know-please-tell-me/165078/9 "2003-03-29T23:30:15Z")
It’s so clear now… ---
**Author:** ![NameAlreadyTaken](https://avatars.discourse-cdn.com/v4/letter/n/97f17d/32.png) [@NameAlreadyTaken](https://boards.straightdope.com/u/NameAlreadyTaken)\ **Post date:** [March 29, 2003, 11:41pm UTC](https://boards.straightdope.com/t/how-does-it-know-please-tell-me/165078/10 "2003-03-29T23:41:22Z")
Another one along these lines is the “missing card” trick (one of many sites): [http://www.cjta.net/special/](http://www.cjta.net/special/) As a hint, every site that I’ve seen with this trick puts in a silly place holder page to count on the fact that most people are only going to concentrate on one thing (the card they picked) rather than what was actually on the page. ---
**Author:** ![DougAB](https://avatars.discourse-cdn.com/v4/letter/d/e47c2d/32.png) [@DougAB](https://boards.straightdope.com/u/DougAB)\ **Post date:** [March 30, 2003, 12:06am UTC](https://boards.straightdope.com/t/how-does-it-know-please-tell-me/165078/11 "2003-03-30T00:06:19Z")
What really burns me is that the guy who programmed the Internet Mind Reader charges money on his website if you want the explanation for how it works! I know he needs to make money, but that doesnt seem like the right way. ``` Then again...it was free... ....damn the internet and it's moral quandries! ```