Joe Crawford has a good debunking of the whole thing on his artlung site.

--Kynn

That puzzle is being spread exponentially (via E-mail) by people that are unlikely to "get it" even after you explain it to them! ;-) It's magic.

I mean, the intersection of people that follow the math and yet cannot realize the issue at hand for themselves must be very small.

I try and explain to my Dad about the odds of winning the lottery, does he listen? No. Why? "Because somebody has to win!" Groan.

The big joke to me is that the puzzle doesn't work if you pick a number from 0 to 9, the formula gives 0 (zero) and the symbol is random at zero ( it should match symbol at 9, etc.) - with over 20 unique symbols (I counted 23) there is less than 5 % chance if you pick "7" (or any number below 10)

This isn't magic.

This, on the other hand, is really magic:
http://y.20q.net:8095/btest

My wife sent me the symbol puzzle yesterday - I explained how it works. Funny thing was one of her friends was so bad at maths she said it had 'read her mind' 2 out of 3 times!

Reminds me of the old mind reader trick with numbers printed on a series of cards (which makes a computerized version easy : )

http://toastdesign.com/mindReader/

It does a couple of clever things to throw off people trying to figure it out. Chris noticed that it puts a random symbol at zero-- that's a nice bit of social engineering; non-hackers won't pick zero as the leading digit. Also, you'll never get 90 or 99 by doing the little manipulation, so it gives random symbols to those too. These things make the multiple-of-9 pattern harder to see on casual inspection. That threw me for a little while, when I purposely tried to spring the puzzle by choosing 10x+y as my number.

My dad sent me this a few days ago. It took me about 2 minutes to figure it out by solving the algebra. Although my dad was impressed to get a rapid reply from me, I didn't give it another thought until I saw it on your weblog. When these comments said it was spreading like wildfire, I googled "Flash Mind Reader" and was surprised by the amount of blog traffic this thing has generated.
I was truly alarmed by the number of posters who could not figure it out. I was even more alarmed by those who could not understand the numerous explanations. The algebra involved is trivial - every 7th or 8th grade student is taught the math skills required. Even without algebra, numerous people sweated out brute-force solutions by evaluating each of the 90 sums (in finite time).
Next time your kid complains, "Why do I have to learn this stuff? I'll never need to know algebra in real life..."; you can answer, "So you don't waste hours trying to figure out stupid internet puzzles..." Of course, it's probably easier to believe in psychic Flash animations and magic java applets.

Wow, brett johnson, arn't you smart? Why not tell us more about how much smarter you are than most people? Isn't it funny that most people don't solve silly little math puzzles as fast as you? Wow, I understand why you like talking about it!

Yeah, click my name to get to it. URL: http://artlung.com/words/flash-psychic-proof/