Thursday, December 8

the Flash Mind Reader

Can you figure out how this works?

click here
Posted by Tom at 12/08/2005

1 comment:

Anonymous said...

That's a nifty trick!

Spoiler Warning: If you don't want to know how this works, don't read the rest of this comment.

The first part of the trick is that there are only 9 possible results for the formula given. If you choose, 10-19 as your starting number, for example, your result will always be 9. 20-29 always yields 18 and so on up to 90-99, which always yields 81.

This is a characteristic of base 10. The result of the given formula will always be a multiple of the highest single digit in the number system you're using. So in base 10 the result will always be a multiple of 9. In base 9 it will always be a multiple of 8, etc.

So, anyway, the possible results are already known and (here's the second part of the trick) those 9 results are always displayed next to a common symbol.

The third part of the trick is that the common symbol changes each time you try the game again. The user wouldn't usually notice that because he likely chooses a different starting number each time and a different symbol is returned. So he assumes that each number has its own symbol that remains constant.

But the truth is that the math puts you in a corral of a certain number set and the symbols are switched to keep you from seeing the fence :>)

Cool blog!

12/11/2005 12:43 PM

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