How does this website read your mind.

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The website discussed utilizes a mathematical trick to create the illusion of mind reading by manipulating two-digit numbers. Users input a number, and the resulting calculations consistently yield gifts that are multiples of nine, which are always the same. The method relies on the formula 10a + b - a - b = 9a, ensuring the outcome is a multiple of nine. Participants express amusement at the simplicity and effectiveness of the trick, contrasting it with more complex number games. Overall, the discussion highlights the clever application of algebra in creating engaging online experiences.
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Hi ,
A friend sent me this website, and I was wondering how it worked,

http://www.regiftable.com/regiftingrobinpopup.html

obviously it can't read my mind, and its some kind of mathematical trick, I can initially see that all the answers i come up with are 18 apart and that gift is always the same, but why.

Jason
 
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Hah,it's a liittle tricky.
Any 2-digital number can be expressed as 10a+b,so what you do in fact is 10a+b-a-b=9a, always a multiple of 9, and you notice that the gifts labled by 9,18,27...are always the same!
 
haha I liked this :biggrin:

Seriously, its not even like those "think of any number, at 20, multiply by 50, subtract 100... etc." sort of doo-wackies. It's so simple it asks for just one thing from you and gets it right every time. I was so stumped as how it was done, lol post #2 spoilt the fun :-p
 
Thanks kof9595995 that explains it perfectly, isn't algebra wonderful.

I've just never seen it applied like that before.

fleem, that's an interesting site too, very clever.
 
teheh, all the multiples of 9 are the same gifts
 
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