# How does this trick work? **URL:** \ **Category:** Factual Questions\ **Created:** [April 29, 2006, 2:41pm UTC](https://boards.straightdope.com/t/how-does-this-trick-work/354739 "2006-04-29T14:41:01Z")\ **Posts on this page:** 13\ **Page:** 1
**Author:** ![Otto](https://avatars.discourse-cdn.com/v4/letter/o/bbe5ce/32.png) [@Otto](https://boards.straightdope.com/u/Otto)\ **Post date:** [April 29, 2006, 2:41pm UTC](https://boards.straightdope.com/t/how-does-this-trick-work/354739/1 "2006-04-29T14:41:01Z")
[http://www.mysticalball.com/](http://www.mysticalball.com/) I’ve run about 50 trials and it’s been right every time. ---
**Author:** ![Bear\_Nenno](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bear_nenno/32/3358_2.png) [@Bear\_Nenno](https://boards.straightdope.com/u/Bear_Nenno)\ **Post date:** [April 29, 2006, 2:51pm UTC](https://boards.straightdope.com/t/how-does-this-trick-work/354739/2 "2006-04-29T14:51:05Z")
The answer is always 0,9,18,22,27,34,36,45,59,63,66,72, or 81!! That’s just how math works. All these numbers will always have the same symbol, but they change that symbol each time. But notice all these numbers will have the same number as the crystal ball. Pretty neat the first two times though. ---
**Author:** ![Stan\_Shmenge](https://avatars.discourse-cdn.com/v4/letter/s/94ad74/32.png) [@Stan\_Shmenge](https://boards.straightdope.com/u/Stan_Shmenge)\ **Post date:** [April 29, 2006, 2:52pm UTC](https://boards.straightdope.com/t/how-does-this-trick-work/354739/3 "2006-04-29T14:52:44Z")
The formula always turns up certain numbers. 66- 66-12= 54 67- 67-13= umm, 54 again! 68- 68-14= wowee, 54 again! The symbols are scrambled, but it will always be the symbol next to 54 and the other numbers that fit the series that comes up. Symple. ---
**Author:** ![Airman\_Doors\_USAF](https://avatars.discourse-cdn.com/v4/letter/a/e36b37/32.png) [@Airman\_Doors\_USAF](https://boards.straightdope.com/u/Airman_Doors_USAF)\ **Post date:** [April 29, 2006, 3:02pm UTC](https://boards.straightdope.com/t/how-does-this-trick-work/354739/4 "2006-04-29T15:02:24Z")
If you take any two-digit number, add the two digits together, and then subtract the sum from the original number the result will always be a multiple of 9. Look at the symbols each time, and 9, 18, 27, 36, 45, 54, 63, 72, and 81 will all be the same. ---
**Author:** ![Airman\_Doors\_USAF](https://avatars.discourse-cdn.com/v4/letter/a/e36b37/32.png) [@Airman\_Doors\_USAF](https://boards.straightdope.com/u/Airman_Doors_USAF)\ **Post date:** [April 29, 2006, 3:05pm UTC](https://boards.straightdope.com/t/how-does-this-trick-work/354739/5 "2006-04-29T15:05:24Z")
Well, then. No need for a spoiler box. **Bear\_Nenno** , however, is wrong. The result will always be a multiple of 9. 22, 34, 59, and 66 can never be results, and he omitted 54. ---
**Author:** ![Airman\_Doors\_USAF](https://avatars.discourse-cdn.com/v4/letter/a/e36b37/32.png) [@Airman\_Doors\_USAF](https://boards.straightdope.com/u/Airman_Doors_USAF)\ **Post date:** [April 29, 2006, 3:26pm UTC](https://boards.straightdope.com/t/how-does-this-trick-work/354739/6 "2006-04-29T15:26:19Z")
One more thing that jumped out at me after a few minutes: this version isn’t even particularly well done. The only symbols that change are the multiples of 9, and once you notice that it’s easy to see. Some of them change all the symbols every time to throw you off the scent, although they still operate the same way. ---
**Author:** ![Bear\_Nenno](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bear_nenno/32/3358_2.png) [@Bear\_Nenno](https://boards.straightdope.com/u/Bear_Nenno)\ **Post date:** [April 29, 2006, 3:32pm UTC](https://boards.straightdope.com/t/how-does-this-trick-work/354739/7 "2006-04-29T15:32:56Z")
> [@Airman Doors](#): > > Well, then. No need for a spoiler box. > > **Bear\_Nenno** , however, is wrong. The result will always be a multiple of 9. 22, 34, 59, and 66 can never be results, and he omitted 54. Ah… 59 was a type and should have been 54… The other three were just coincidintally the same symbol as my answer on that interation, I’m guessing. I didn’t realize the multiple of 9 thing. I just noticed that there was a limited number of possible answers, and that they were all covered with the same symbol. ---
**Author:** ![racer72](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/racer72/32/3075_2.png) [@racer72](https://boards.straightdope.com/u/racer72)\ **Post date:** [April 29, 2006, 5:06pm UTC](https://boards.straightdope.com/t/how-does-this-trick-work/354739/8 "2006-04-29T17:06:43Z")
> [@Airman Doors](#): > > One more thing that jumped out at me after a few minutes: this version isn’t even particularly well done. The only symbols that change are the multiples of 9, and once you notice that it’s easy to see. > > Some of them change all the symbols every time to throw you off the scent, although they still operate the same way. Not true. I just ran it 10 times and the number 98 had 7 different symbols. ---
**Author:** ![Airman\_Doors\_USAF](https://avatars.discourse-cdn.com/v4/letter/a/e36b37/32.png) [@Airman\_Doors\_USAF](https://boards.straightdope.com/u/Airman_Doors_USAF)\ **Post date:** [April 29, 2006, 5:08pm UTC](https://boards.straightdope.com/t/how-does-this-trick-work/354739/9 "2006-04-29T17:08:44Z")
Fair enough. I looked at 36, 45, and 54 and the symbols never changed around them, which led me to say that. I’ve seen some where they all change, so I still say that this one wasn’t particularly well done. ---
**Author:** ![panache45](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/panache45/32/64_2.png) [@panache45](https://boards.straightdope.com/u/panache45)\ **Post date:** [April 29, 2006, 7:17pm UTC](https://boards.straightdope.com/t/how-does-this-trick-work/354739/10 "2006-04-29T19:17:45Z")
The procedure is: (10x+y)–(x+y) which is 9x. So the final number is always 9 times the first digit, and therefore must be a multiple of 9 ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [April 30, 2006, 4:30am UTC](https://boards.straightdope.com/t/how-does-this-trick-work/354739/11 "2006-04-30T04:30:40Z")
> [@Otto](#): > > [http://www.mysticalball.com/](http://www.mysticalball.com/) > > I’ve run about 50 trials and it’s been right every time. With tricks like this, you’ll quickly see the solution if you run several trials without completing the trick. ---
**Author:** ![Eleusis](https://avatars.discourse-cdn.com/v4/letter/e/f4b2a3/32.png) [@Eleusis](https://boards.straightdope.com/u/Eleusis)\ **Post date:** [April 30, 2006, 5:42am UTC](https://boards.straightdope.com/t/how-does-this-trick-work/354739/12 "2006-04-30T05:42:44Z")
Seriously, **Otto** , this question has come up at least **100** times. ---
**Author:** ![Eleusis](https://avatars.discourse-cdn.com/v4/letter/e/f4b2a3/32.png) [@Eleusis](https://boards.straightdope.com/u/Eleusis)\ **Post date:** [April 30, 2006, 5:54am UTC](https://boards.straightdope.com/t/how-does-this-trick-work/354739/13 "2006-04-30T05:54:25Z")
> [@Otto](#): > > [http://www.mysticalball.com/](http://www.mysticalball.com/) > > I’ve run about 50 trials and it’s been right every time. > [@Eleusis](#): > > Seriously, **Otto** , this question has come up at least **100** times. Actually, the actual ratio is probably actually correct. I fucking _hope_ you didn’t run it fifty times. :rolleyes: