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Crystal Ball Puzzle

PostPosted: Mon Jan 16, 2006 7:37 pm
by GarySutherland
Can computers read minds? Try out this puzzle and see for yourself:

Crystal Ball Puzzle

This is just one of Andy McNaughton's excellent Shockwave puzzles. There are more on his website.

Can you work out how it works?

Cheers
Gary

PostPosted: Mon Jan 16, 2006 10:45 pm
by dgraves
Gary, that is one craaazy game :shock: :lol: . You can't look back at your answer or the thing "knows". You have to concentrate hard to fool it.

PostPosted: Mon Jan 16, 2006 10:53 pm
by Bobbie En Tejas
That is weird! I thought I had seen this before, but I figured out that one. This is different, I could see how it would work if you actually had to click on something, but you aren't. Okay Gary, spill your guts! How does it work! (Before it drives me crazy) :shock: er...

PostPosted: Mon Jan 16, 2006 11:10 pm
by GarySutherland
It is quite a good one, isn't it. I think I'll keep my own counsel for a while yet before revealing how it works. Just look for the pattern...

Cheers
Gary

PostPosted: Tue Jan 17, 2006 1:10 am
by John A
took me a couple of goes but have now worked it out :lol:

PostPosted: Tue Jan 17, 2006 4:56 pm
by kintyre 84
Sometimes I think I am quite clever... but this has me stumped ...
I understand the nine connection but how does it know which one you have chosen... Really good puzzle ....

PostPosted: Wed Jan 18, 2006 9:58 am
by witchnettle
its an excellent puzzle, but i am happy to say (she says smuggly) I have worked it out.... Get off the floor Gary, I had a wee tiny bit of help from some clever friends and an algebraic equation, (now that bit had me completely stumped, but i took their word for it) xxxxxxxx

How it works....

PostPosted: Wed Jan 18, 2006 3:02 pm
by GarySutherland
OK, some of you have sussed that the computer isn't really reading your mind and that there is some trick to it. Some of you have even worked out how it works, or so you say.

Well, yes there is a trick and here's how it works...

Regardless of which 2-digit number you choose, after you've subtracted the sum of its component digits the range of results you can get is strictly limited to numbers in the series 09, 18, 27, 36, 45, 54, 63, 72 and 81.

None of the other numbers on the chart can be reached by following the calculation in the puzzle. Try it and see.

It's then a simple job for the computer to choose a symbol at random and make sure that those numbers in the series are all given that symbol when it's drawing the chart; the other numbers are given a random symbol which acts to camouflage the patter.

It's still a pretty good puzzle though.

Cheers
Gary