Very OT: but fun

Ran across this link

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. My spyware/trojan/adware scanner does not ping so I think it's safe. For those who don't like clicking on unknown URL's, it is a card trick. It shows you six picture playing cards, king of hearts, jack of clubs etc. and invites you to pick one. You then "click here". It then shows you five playing cards and the one you picked is no longer there. And it works every time. Would you believe that I could not work out how the trick was done? I looked at the source code of page and was not enlightened, though I should have been.

I then thought I would ask the guys on aus. electronics if they could figure out how it worked. You know, a fairly bright bunch who have never failed me yet when I asked about something that was actually on topic.

Fortunately, before I made a complete moron of myself, I figured it out for myself. I must have led a very sheltered internet life to be taken in for a good fifteen minutes. See below for how it works.

> > > > > > > > > > > >

The first .gif is of six picture cards. The second .gif is of five picture cards, NONE of which are the same as the first six. So the one you picked is not there but neither are any of the others. Duh. Is this a case of "hiding in plain view" or "can't see the wood for the trees."?

PH

Reply to
Peter Howard
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OK, how do you think this "mind reading" game works....?

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Bob

Reply to
Bob Parker

Hmm, interesting one, Bob. There are only nine possible answers. 9 and its multiples up to 81. All the other numbers are there only to obscure the issue. The game fools people like me by changing all the symbols in the chart every time you play. However, 9,18,27--->81 always share the same symbol, whatever it is for the particular round, which then comes up in the crystal ball. It seems to work for three and four digit numbers too. Only a limited number of answers, each one nine more than the previous one. There must be a mathematical name for this phenomenon but I'm blowed if I know what it is. I'm one of those unfortunates with a blind spot when it comes to maths so I never went further than 10th grade Maths for Dummies. I'm awestruck by people like Isaac Newton for instance, who invented calculus with a quill pen by candle-light.

PH

Reply to
Peter Howard

You're doing better than me! I couldn't figure it out, so I searched the net till I found the explanation. Well done!! There wouldn't be many people with the imagination and natural mathematical skills of Newton, Charles Babbage or Alan Turing etc. I'm definitely a very long way below that intellectual level. :)

Bob

Reply to
Bob Parker

On Wed, 23 Nov 2005 12:46:42 GMT, "Peter Howard" put finger to keyboard and composed:

It's called "algebra".

Let the number's digits be X and Y.

Therefore the number's value is 10X + Y

Result of subtraction is (10X + Y) - X - Y = 9X.

The possible values for your result are therefore 9, 18, 27, ..., 81.

-- Franc Zabkar

Please remove one 'i' from my address when replying by email.

Reply to
Franc Zabkar

Even Newton acknowledged the "giants" whose shoulders he stood on. Where would he have been without that quill pen?

Reply to
T.T.

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