How does this Crystal Ball thingy work?

Crystal Ball

Since this has a factual answer, I’ll move it to GQ for you.


Cajun Man ~ SDMB Moderator

Once you add the sum of any two didgit number, and the subtract that sum from the original, it’s always a multiple of nine.

The only possible numbers are:

81
72
63
54
45
36
27
18
9

And those are always the same symbols

Your link is taking forever to load for me, but it sounds like the same thing Snopes describes here.

Others too have wondered this:

http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=163712
http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=169075
http://boards.straightdope.com/sdmb/showthread.php?s=&threadid=166356