Mind Reading on Internet!
Recently one of the regular QuickerMaths visitor stumbled upon a website that claims to read your mind using some sort of math trick. He got perplexed that how is it possible? How come every time it gives correct answer? He asked me if I could unravel the secret. Fortunately I could. I am sure many of you would be able expose the trick behind this mind reading game. At least all of you should try.
The website is called Regifting Robin. It asks you to pick any 2 digit number and then subtract the digits of the number from your two digit number. Say you pick 37. Then you do 37 - 3 - 7 = 27.
On the next screen, you are given grid of numbers, numbered 1 - 99. You are instructed to find the box with your number (in this case, 27) and read the name of the gift inside the box. Click next and Robin tells you the gift you selected. You can check this works every time.
Try it yourself
First of all you try it yourself, here’s the link to that website - http://www.regiftable.com/regiftingrobinpopup.html
So how does it work?
People who want to learn many such mind reading tricks can refer to the book - Easy Mind-Reading Tricks by Robert Mandelberg and Ferruccio Sardella.
Mr. Sagar has explained the secret behind this mind reading trick beautifully in the comment below. I am just reproducing the comment below for everyone's convenience -
"This Mind Reader will use mathematics to create the illusion that this technique is reading your mind. A person select a number AB (where A will be the very first digit and B the 2nd digit). The end result of your calculation are going to be:
(10A +B) – (A + B) = 9A.
Which means that, what ever B you select, your answer could only be one of the following 9 numbers (given A between 1 and 9): 9, 18, 27, 36, 45, 54, 63, 72, 81. When you look at the table of numbers and symbols in the mind reader, you will see that the symbols change each and every round in order to confuse you, however in any given round, the symbol is always exactly the same for these 9 numbers. Your computation actually provides a ultimate result associated with the unique symbol assigned to the 9 possible solutions."
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