http://trunks.secondfoundation.org/files/psychic.swf

Ehmm... maybe it's just after a hard day's work, but I can't for the life of me work out how this works.

I figured it out once. I can't remember though.

Something about all the possible numbers adding up to one of the numbers that shares a sign with the other possible ones. I think.

Yep, see... 36 is one of the possible numbers. It'll always be that symbol

It's obvious.

Try the same number twice :p

There are only a finite number of "Final answers" possible with the given instructions. Each answer has the same symbol. Use the example at the bottom (final answer 18), and match it to any combo you can think of. the symbols are always the same for all the answers, but the actual image can change every time. Again, watch 18 and the image changes every time.

How about that, it still works...

It's fun... and a bit like 'bwaaaah?' the first time :D.

The formula provided always gives a multiplication of 9, and they all share the same icon on any given try (the 9 icon changes between tries). 9, 18, 27, etc. all have the same icon.

[edit]Fardreamer's method is a lot easier for working out which numbers the symbol appears at, my method tells you why they appear where they do.[/edit]

its really simple when you think about it, although it did get me the first time I did it about 3-4 years ago until I started thinking about it.

lets choose the first few two digit numbers for example.

say you choose 10, answer = 10-(1+0) = 9
say you choose 11, answer = 11-(1+1) = 9
say you choose 12, answer = 12-(1+2) = 9
say you choose 13, answer = 13-(1+3) = 9
say you choose 14, answer = 14-(1+4) = 9
say you choose 15, answer = 15-(1+5) = 9
say you choose 16, answer = 16-(1+6) = 9

guess where there is a "magic" symbol.........9

I'll try and explain in words...

basically the "magic" symbol will always be the first digit of places below the multiple of 10 of the first digit of the number you choose....(hope that makes sense).

if you choose 43, the symbol will be 4 places below 40 (ie 36), if you choose 78, it'll be 7 places below 70 (63).

or for the more mathematical reason why it's always a multiple of 9...

A two digit number is represented as 10*a + b (0 <= a <= 9, 0 <= b <= 9).

The final number is calculated as follows:

original number - (digit 1 + digit 2)

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

Remember that 0 <= a <= 9, so the only possible values go up to 81, which is why 90 and 99 don't need to be the same figure as the other multiples of 9.

These math tricks always have something to do with 9, don't they.

That 9 just thinks he's so cool...
Everyone knows how to do mutliples of 9 on their fingers, and how multiples of three can add their digits and it's still a multiple of 3

Ahh... didn't actually notice that the symbols change each time.

Bah, I feel so stupid.

Seven ate nine.