In one of their TV appearances on the Tonight Show, they performed an intriguing trick that involved all members of the audience. Each person received four cards which were torn apart and "mixed" so to have two out of the eight halves selected in a process that seems random, as each person has freedoms of moves throughout the process. Yet, in the end, every one ends up with two halves of the same card. Some mathematicians made a deep analysis of the trick and generalized it so it would work with any number of initial cards, using mathematical induction; their complete analysis was published in the Journal of Magic Research.