Puzzling Cybernetics

No matter what 2 digit number you pick, deducting its two component numbers will produce a number divisible by 9. Since the maximum answer you can get by doing this is 81 you will find that at closer inspection every number that is divisible by 9 up to and including 81 has the same symbol

Did you know this one or did you just figure it out now? Your answer is darn clever!!!

I did it once and was very impressed....so impressed I did it again which is where the illusion let itself down It was the same symbol. Third time confirmed my suspicions.

A good magician will not perform the same trick twice because they rely a great deal on the element of surprise.

There was one like this a few years ago based on cards. It would predict the card you chose. Very clever, but as you say, after a few times, the magic was gone.

Well done!!!

Thank you

This trick is a function of an old accounting check. It is call "casting out nines". It was very useful before electronic calculators.

http://en.wikipedia.org/wiki/Casting_out_nines

Do not know but it did not work, i tried 5 times and only the 1st it was ok

Casting out nines definitely works, and the puzzle on the web page definitely works. So what didn't work???