Anyone got an idea of how this works???

http://www.able2know.com/forums/viewtopic.php?p=118986#118986

Wow!! that was great. Right up my street.

very easy

ive seen it before

each time you get a 9. Why? like this:

10*a+b = number
a+b = sum of digits

10*a+b-(a+b) = 9*a

which is always a multiple of 9. Notice that every multiple of 9 has the same symbol, and the symbol is changed each time. Therefore, it will always be the same symbol

as a math major i should know that

Thanks Tech -- somewhere, over in the other site, I found out the answer -- and of course, since it seems so easy once you know the gimmick, I slapped myself in the head.

Good puzzles in A2K.