MATHEMATICS BEHIND THE MAGIC

MIND READER

          

You might have come across mind reader, but ever wondered how it works. How it is able to give you the exact symbol each time. You can check out the mind reader from this site or download it from here.

What it does ?
Select a two digit number. Add the two digits and subtract it from the original number. You are not to disclose any number at any time. The symbol ahead of the result will be displayed. Check out this magic. It really works.

Let us see the Mathematics behind the Magic.
Select any two digit number. You can select any number from 10 to 99. Right ? This number can be expressed as 10x + y. Comfortable. ? For eg if you want to make 56 then x is 5 and y is 6, so that 10*5 + 6 = 56.


Now add both digits. i.e. 5 + 6 = 11
I shall add them x + y. Right !!!

Now subtract the result from the original number, means 56-(5+6) = 56-11 = 45. Right !!
I shall do the same now with algebra. 10x+y-(x+y) = 9x.

You see your symbol and press the button. The symbol that is displayed is same as you got.


Now from my answer which is 9x, it implies that for whatever value of x or y you take, you will always end up with a multiple of 9 as your final answer. And the trick is that all the multiples of 9 means the numbers 9,18,27,36,45,54,63,72,81,90 and 99, they all have the same symbol in the game. The symbol changes at all places in the next try but all these places hold a similar symbol again in the next game (though the symbol being a new one now).

So whatever number you select I can tell you what symbol you will arrive at.