I've come across an interesting site (which was advertised on another site I found through StumbleUpon), featuring a supposedly mind-reading magic square.
This site gets the user to choose a two digit number at random, and then subtract from this number the values of its digits, e.g. if you chose 87, you would then subtract 8 and 7 from 87 to get 72. You then look at a grid showing numbers and symbols, and find the symbol corresponding to your result.
The site tells you it will guess your symbol correctly three times, then if you pay $2 via PayPal, you can get five more guesses and a presentation about the "Secret to Life". And you can pay $20 to have the secret of the magic square explained to you.
Of course, there is no magic, and no mind-reading, and a bit of elementary maths can quickly reveal what's going on. This is actually a good exercise for both Mathematics and Computer Studies classes - construct a spreadsheet or computer program that shows all the numbers from 10 to 99 and the result after subtracting the number's digits from itself. Once you've done that, the trick is obvious.
What about the "Secret to Life"? I didn't pay to find out, but I suspect it might be that a fool and his money are soon parted.
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A discussion of Mathematics and computer programming and why logic is disappearing from public life.
1 comment:
It scares me that my dad who, while he's 83 and not quite so sharp anymore, was an accountant and should have been able to figure this problem out (there are MANY versions, though all grounded in identical math; you seem to have found one that tries to actually make MONEY on the deal, however, which I had not yet bumped into), was so quick to find himself baffled by it. He's hardly alone. It keeps making the rounds on various blogs and discussion lists.
I guess I saw enough "math magic tricks" as a kid to realize that they're going to be solvable, and probably with simple algebra or a little careful arithmetic thought. Not to make my dad out to be typically lazy, I do think there are a shocking number of folks who SHOULD know better who get dazzled by this sort of glitz, especially when computers are involved. :)
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