Mistake Card Force
A spectator names a number from 10 to 30 and the magician counts down to the card. Amazingly it matches the previously written prediction, or you have just forced a spectator to take a card that you already know what it is, so you can proceed with your own variation.
You force a card by mistake! You must pretend to mess up for this to work. Place the card that you want to force to them in the seventh position in the deck.
Ask them to name any number from 10 to 30.
For example, they say 16.
Start counting cards down onto the table into a pile. One, two, three, four,...Keep counting but go past 16. 16 + 7 = 23. So go to 23 and say, "Whoops. I went to far...here you better do it! It'll be more fair that way anyway!" Pick up the 23 cards and put them back on the deck.
What you have just done is placed the force card in the exact position of the card they are going to stop on!
Have them do exactly what you were supposed to do and when they get to number 16 that will be the card.
Other tips for this card trick:
You don't have to always use 10 to 30. You could use other numbers. It just wouldn't make as much sense if someone said 2, and you counted all the way to 9, right? You could expand it to 5 to 40, but 5 would still be pretty short, and 40 would be so long you might lose some of the excitement of the trick.
Very cool idea for how to force a card, huh? Nice thing is, it takes only a second or two to learn how to do it, and then you can do it with a borrowed deck.