Mind-reading machine

[Lord Muck oGentry]

Over at JREF they are giving this chestnut another turn over the fire:

http://www.ecardtricks.com/mr4.htm

If you haven't seen it before, tell us what you make of it.

[Admin]

That's an easy one to work out.

It always gets you at first though as it's quite clever so I won't reveal the answer in case anyone hasn't tried it.

[Cuddles]

I've never understood how people can be fooled by that.

[bobdezon]

It didnt work on me, it incorrectly guessed 5 wrong cards. ::)

[Matt]

I had seen it before - as a powerpoint. It's quite a smart little trick but easy to figure out. The trouble with computers doing majic triacks is you think you've figured it out so you ask to see the trick again. Whereas a real life magician will keep you guessing, perhaps acheiveing a similar effect through a different method to fuirther misdirect you the computer really is a one trick pony. You can get it to go over and over until you suss it out.

As I remember my first guess was correct. I was helped by the fact that as it was a simple powerpoint I knew that the trick was comptely passive. At least on the web someone might think that they get a different set of five cards displayed depending on which of the initial 6 they chose.

[Lord Muck oGentry]

I've never understood how people can be fooled by that.


Someone else at JREF has posted a link in which explanations are offered:
http://sprott.physics.wisc.edu/pickover/esp4.html

[ Warning: contains serious abuse of scientific terms] :-)

The answer to your question may be that some people are willing to entertain any explanation other than " It'a trick".

[Muttley]

I must admit I hadn't seen this before, and it's quite uncanny to start with how it keeps getting the right answer.

It's also surprising, looking at the link above, how so many people haven't figured out how it works.

I didn't even approach it scientifically (being on the wrong side of half a bottle of wine). I wrote down what the starting cards were, didn't pick one, then checked to see which one had disappeared. At which point it all became blindingly obvious. O0

[bindeweede]

I've never understood how people can be fooled by that.

Well, I was - no real surprise. So, the second time, I made a note of the cards, and........................^-^

[bindeweede]

I came across something similar


http://www.milaadesign.com/wizardy.html

[Matt]

I came across something similar


http://www.milaadesign.com/wizardy.html

OK I can kinda see why this works but are there any number theorists out there who can explain in simple terms why if you pick a two digit number and subtract the sum of it's digits the result is always a multiple of 9.

Best I can come up with is if you subtract the "units from" any two digit number, you'll get a number divisible by 10, So 10, 20, 30, 40, 50, 60, 70, 80 or 90

If you then subtract the "tens" you get a number divisible by 9
9, 18, 36, 45, 54, 63, 72 or 81

Of course subtract the digits separately is the same as subtracting the sum of the digits.

[MRT]

I thought it was just plain annoying! But then, I think all so-called 'magic' is annoying. I've never considered conjuring so much an entertainment as a waste of a precious part of my life. It's like juggling - after you've seen it once, why would you ever want to see it again? Just what I think ...