Re: OT: Unbelievable

Quoting BP Jonsson <bpj@...>:

> My fiancee was directed to this:
>
> <http://mr-31238.mr.valuehost.co.uk/assets/Flash/psychic.swf>
>
> Is there a mathematical explanation to this?
> Not that I would understand such an explanation,
> but I'd like to know if there is one.
There is, a soon as you realize the Golden Rule of Obviousness; thou shall
choose a two-digit number the first digit of which is non-zero. My first two
choices were 00 and 09, and I started to wonder why anyone'd make a hoax mind
reader that does not even appear to work ...

The explanation is quite simple; I think you'll understand. In mathspeak, we
choose a number X, which in our decimal notation is written as 10*a+b. Then we
subtract the sum of the digits; new number 10*a+b-(a+b)=9*a . Thing is, the
thing always gives the same symbol for all the multiples of nine (except, for
some idiot reason, zero, which gives rise to the Golden Rule of Obviousness).

If that was too mathy, I'll try do it with more words and less mathese.
Suppose we choose 84. Jolly good number, Orwell would probably not have told
us. Lets add the digits together; 8+4=12. However, for reasons that will
become apparent, it's much easier to think of it as just 8+4 (in other words,
they tell you to add the things together just to confuse you). So, we subtract
first four and the eight from our starting number; 84-4=80. It should be
obvious by now that no matter what number we choose, we'll at this stage have
a multiple of ten. Then we substract again - to be precise, we subtract the
thing ten is multiplied by, namely eight; 80-8=72. It's easier to see what's
going on if we write this as 8*10-8=8*9=72. I hope you see we'll always get a
multiple of nine this way. And again, the script provides the same symbol for
each multiple of nine (again, except, for no reason I can see, zero).

                                                          Andreas

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