Dan gives a clear explanation, so that even if someone is not familiar with the invisible deck, he
can easily learn this affect. The advantage to this effect, besides being able to use in parlor or
stage magic, is that one does not even need to think of the math - making it really simple. Dan
gives hints for the handling and for the production bag. I would make the bag using white paper
(like a bakery bag) instead of the brown kraft paper in order to match the white edges of the
cards.