The Flash Mind Reader relies on the fact that the formula used to compute the number of which you're supposedly thinking always produces a multiple of 9. Multiples of 9 in the list of symbols all have the same symbol beside them and this is the symbol that appears when you click on the crystal ball.
An Fear Rua explains why
Mícheál Ó Muircheartaigh is regarded as a national treasure in Ireland, even by
GAA apostates like me.