I learned the following effect and would like to knwo who the creator / author is so I can give him proper credit. I am not posting the "secret" only the effect.
If anyone knows the orgin, please contact me at firstname.lastname@example.org
You have seen or heard of many ways in which a performer can ascertain what cards have been selected by his audience. I have developed a science which gives me 100% accuracy without seeing a card, touching a card, in fact, without using any cards at all. I call this science Cardology.
All of you are invited to participate in this demonstration, and I hope time will permit me to answer all. Simply follow my instructions, and as you complete this test in Cardology, raise your hand.Ready?
I want you to think of any card in the deck, double its value (if it's an ace count it as one, two as two, etc., up to ten. If you think of a jack the value is eleven, Queen is twelve, and King is thirteen.
Now, after doubling its value, add one and multiply this total by five. Has that been done? Fine.
The performer continues, "You, sir, say that your total is 74; then the card you thought of was the 6 of spades. That is correct, you say? Thank you."
"This gentleman has 131, and he thought of the queen of clubs. The lady who called out 82 was thinking of a 7 of diamonds. Thank you."
"For your answer to 53--you, sir, thought of the 4 of hearts. Thank you, ladies and gentlemen, for helping me."