# My Mathematical Magic Show: Part 6

Last March, on Pi Day (March 14, 2015), I put together a mathematical magic show for the Pi Day festivities at our local library, compiling various tricks that I teach to our future secondary teachers. I was expecting an audience of junior-high and high school students but ended up with an audience of elementary school students (and their parents). Still, I thought that this might be of general interest, and so I’ll present these tricks as well as the explanations for these tricks in this series. From start to finish, this mathematical magic show took me about 50-55 minutes to complete. None of the tricks in this routine are original to me; I learned each of these tricks from somebody else.

After presenting four different but thoroughly impressive mathematical magic tricks (including the explanations for each trick as well as a chance for a child in the audience to present the trick for themselves) over the past 50-55 minutes, I have now reached the climatic end of my routine.

Here’s the patter for my grand finale. I got this trick from a book of card tricks that my parents bought me when I was a boy. (The book remains one of my prized possessions from my childhood.) This trick requires an ordinary deck of playing cards — preferably a newly purchased, sealed, and unused deck of cards.

It’s now time for the final magic trick of the show. And every magic act has to include a magic trick involving… a deck of cards.

Now, when most magicians perform a magic trick, they have a deck of cards that are pre-arranged in a certain order. But I am not like most magicians. (I hand the deck to someone.) Here, please take the deck of cards and shuffle it a few times. (He shuffles the deck and gives it back to me.)

Now, when most magicians perform a magic trick, they have a confederate in the audience who helps me cheat by shuffling the deck in a certain way. (Laughter.) But I am not like most magicians. (I hand the deck to someone else.) Here, please take the deck and shuffle it a few more times. (She shuffles the deck some more and gives it back to me.)

Now, when most magicians perform a magic trick, they ask someone in the audience to take a card from a certain spot in the deck. But I am not like most magicians. (I hand the deck to a third person.) Here, please choose a card from anywhere in the deck, and show it to everyone. (The third person picks a card and shows it to everyone except me.)

Now, when most magicians perform a magic trick, they have the card returned to a certain spot in the deck. But…

(And the audience invariably says, “You are not like most magicians!”)

Oh, you’ve seen this trick before?

That’s right, I’m not like most magicians. So don’t return that card to a certain spot in the deck. Instead, place it anywhere in the middle you want. (The third person places the card back in the deck.)

Now, when most magicians perform a magic trick, they’ll do something special to the deck so that the card pops out. But I am not like most magicians. Take the deck, and shuffle it again, and then give me back the deck. (The third person shuffles the deck and returns it to me.)

Now, when most magicians perform a magic trick, they search through the deck to find the selected card. But I am not like most magicians. So I will place the deck behind my back and select your card.

(I place the deck behind my back, wait about 10 seconds as if I’m trying to find the card, select a card, and then show it to the audience with complete and utter confidence that I’ve found the right card.)

At this point in the routine, there is one chance in 52 that I drew the correct card. If that happens to happen, then I would take a deep bow and end the show. If someone asks how I did it, I would explain that magicians have to keep some tricks a secret.

However, I’ve performed this trick dozens of times over the last 30 years, and I have yet to select the correct card even once. So, in the highly likely event that I pull the wrong card, the audience will say something like, “No, that’s not it.” I turn to the audience with a straight face, shrug my shoulders, and say,

And that’s the end of the show as the audience howls in laughter.

It’s really important to perform this “trick” after performing several real magic tricks. Indeed, after seeing a few highly impressive mathematical magic tricks, the audience is expecting me to pull out the right card, and the deliberately repetitive patter above builds the tension in the room as the audience tries to figure out how on earth I’m going to pull out the correct card from a thoroughly shuffled deck.

It’s also important to get in touch with my inner Bud Abbott or Super Dave Osborne or any of the legendary straight men of comedy, as I can’t so much as smile during the routine lest I give away the joke.

If anyone complains, I explain that this was a mathematical magic trick… after all, the probability of me pulling the correct card is $\displaystyle \frac{1}{52}$.

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