If you like self working math card tricks then you'll definitely like this one as well!
It requires no preparation and it is also very easy to do - you just need to follow the steps and you'll get your result ;)
I hope you'll like it ;)
From well shuffled deck magician takes out his lucky number card and place it face down on the table
Spectator is instructed to do the same - take out his lucky number card, remember it and place it face down on the table
Spectator is asked to take his calculator and do some simple math with his lucky number - after all math is done, result reveals not only number chosen by spectator but also number that was chosen by magician!
Tell spectator that you'll take your favorite number from the deck - in reality, search for any card with value "3" - lets say 3 of Spades - and place it face down on the table
Ask spectator to do the same - to find his favorite number card and place it face down on the table; remember to stress that he needs to select NUMBER card, not PICTURE card!
Ask spectator take his calculator and do following: take his selected number, multiply by 2, add 2, multiply result by 5 and subtract 7 - it means (? x 2 + 2) x 5 - 7
As soon as he gets the result, he will announce it and then you'll immediately know his chosen number (= first number of the result)... at the end point out that spectator also managed to find your luck number (= second number of the result)