# Can anyone figure this out?

Discussion in 'Community Discussion' started by Legolamb, Jan 12, 2007.

1. ### Legolamb macrumors 6502a

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#1
2. ### Markleshark macrumors 603

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Carlisle, Up Norf!
#2

Erm... Yeah, id like to know how that works.

First I thought it was a mouse over thing, but nope...

Edit: Ok, that scares me. If it helps the numbers do not go with the same symbol everytime.

3. ### someguy macrumors 68020

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Still here.
#3
When you subract the sum of the two digits in any two-digit number from that two-digit number, you get a multiple of nine. The same symbol is then placed beside every multiple of nine (as well as a few random other numbers for illusion's sake).

4. ### Markleshark macrumors 603

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#4
Quicker than me, oh well, esay to work out in the end I guess.

Damn good though.

5. ### Max Payne macrumors 6502a

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Brisbane, Australia
#5
This is a very old trick. I have been seeing it for 7 years now. As someguy said, it's a mathematical trick and the symbols change every time you reload the puzzle. Quite simple if you think about it.

6. ### calculus Guest

Joined:
Dec 12, 2005
#6
It's because there are only a certain number of possible answers when you do this (9, 18, 27, 36, 45 etc I think) and the symbol for each possible answer is the same.

Joined:
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Still here.
#7
That too.

8. ### Legolamb thread starter macrumors 6502a

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#8
You're goooood. I was so wowed by the trick, I failed to pay attention to the display. Like all magic tricks....

9. ### SilentPanda Moderator emeritus

Joined:
Oct 8, 2002
Location:
The Bamboo Forest
#9
Yeah I mean... first you have to pick a 2 digit number. We'll have XY as ours (one letter for each digit).

You are supposed to add X and Y together then subtract them from XY. The addition is just a distraction though.

XY - (X + Y) = XY - X + -Y.

Just subtract Y first. Now you have X0. So before you subtract the ones position you are guaranteed to have X0. Everytime. Basically although you have "free choice" you really are limited to 10, 20, 30, 40, 50, 60, 70, 80, and 90. And you are then forced to subtract X which is the tens digit. Therefore you'll either get 9, 18, 27, 36, 45, 54, 63, 72, 81. Which are all divisible by 9.

Any time you are given free choice of a number and told to manipulate it... you're manipulating it towards a known.

10. ### Markleshark macrumors 603

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Carlisle, Up Norf!
#10
It only scared me when I got pissed off with it, clicked next a few times went 'Right, **** you, 27' and it guessed it right... Because I'd chosen 27. Lol.

11. ### MacBoobsPro macrumors 603

Joined:
Jan 10, 2006
#11
I am absolutely shocking with numbers. Infact I got an 'e' twice I genuinely think I have dyslexia with numbers (whatever that would be called).

Anyhoo... I figured it out pretty quickly. So I am pleased with my self. Woohoo!

Look at me now Mr Shepherd and you said I would never amount to anything.

### Staff Member

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Aug 16, 2005
Location:
New England
#12
Another way to make it clear what's going on is

"XY" - (X + Y) = 10*X + Y - (X + Y) = (10 - 1) * X + (Y - Y) = 9 * X

Just collect like terms, all the Xs go together and the Ys.

B

13. ### Legolamb thread starter macrumors 6502a

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#13
I know it's simple once you know how it's done. But this was a very elegant way of trickery, and one that amused me even when I went back to it.
Can you recommend any other mind bending/ eye candy sites like this one?

14. ### Abstract macrumors Penryn

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Location Location Location
#14
The only reason I was a bit scared when they asked me to stare at the symbol for a long time was because I thought this may be one of those websites that distracts you for like 30 seconds, and then very suddenly, a scary picture pops up and you hear loud screaming coming from your speakers.

15. ### After G macrumors 68000

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Aug 27, 2003
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California
#15
I would have thought it was magic, but I just happened to look at another multiple of 9 that wasn't the one that I got. That ruined the whole thing for me pretty much

### Staff Member

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Sep 19, 2002
Location:
Los Angeles
#16
Although the mathematical explanations above are correct, math is often hard for some people to follow. Occam's Razor says to go with the simplest solution, which means that a better explanation is that
They read your mind!

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#17

B

18. ### SkyBell macrumors 604

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Sep 7, 2006
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Texas, unfortunately.
19. ### Quboid macrumors 6502

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Oct 16, 2006
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everywhere
#19
That thing was mad easy to figure out. I just did it twice and then the trick was staring me in the face.

Very similar to http://mysticalball.com/