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Home / Science, Engineering & Maths / Maths / An Introduction to Recreational Math: Fun, Games, and Puzzles / A Mathematical Card Magic Trick

A Mathematical Card Magic Trick

Watch Yossi Elran perform a math magic trick
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Are you ready for our first magic trick? Cards are great for magic tricks. Here’s a card trick attributed to Martin Gardner. And to help me with this magic trick, Is Orel, Hello Orel!
12.9
Orel: Hi!
13.7
Yossi: Orel is very shy and, so we’re going to do the shy card trick! and so I’ve taken here seven cards from a deck of cards - check them - they’re regular playing cards,
26.7
Yossi: Yes?
26.7
Orel: Yes! No special whatever?
28.3
Orel: No!
28.3
Yossi: Good! So, now, what I’d like you to do is I’d like you to choose one of these cards. Choose whichever card you like. Any card. Show it to the camera but not to me…
40.4
Orel: OK!
40.4
Yossi: OK?
40.4
Orel: Huh huh! and, OK, so give it me back… …and by the way these cards they’re regular playing cards there’s no markings on them whatever, Now, for this card remember it’s the shy playing card trick… I’d like you to choose a number, any number.
59.2
Orel: Five
60.3
Yossi: Five!
60.3
Orel: Yes!
60.3
Yossi: Are you sure?
60.3
Orel: Yes!
62.3
Yossi: You want to change?
62.3
Orel: No!
62.3
Yossi: No! Five! We’ll go with five! Ok! So what I’m going to do now… is I’m going to count every fifth card and expose its face. and you’ll see that your card is so shy it will never expose its face.
80.6
Yossi: OK?
80.6
Orel: OK!
80.6
Yossi: So let’s go then! 1,2,3,4,5… and this is not your card right?
92.6
Orel: No!
92.6
Yossi: No! It can’t be your card because your card is… the shy card, right? so we’re going to keep this card face up to remember that its already shown its face OK! and let’s continue… 1,2,3,4,5… and this is not your card either, right? because your card is the shy card. and we’re going to keep this card face up. 1,2,3,4… and is this your card? …5, is it?
127.2
Orel: No!
127.2
Yossi: No! It can’t be because your card is the shy card it won’t show its face. OK! Let’s carry on! 1,2,3,4,5 - is this your card?
141.6
Orel: No!
141.6
Yossi: No? It’s not the 4 of hearts? No! because your card is the shy card. 1,2,3,4 - is it this card?
153.2
Orel: No!
153.2
Yossi: No! It’s not your card… No! See it’s… in fact…yes…well there are two cards left So, do you think it’s going to be one of them? Let’s see… 1,2,3,4… is it this card? The eight of diamonds?
167.1
Orel: No!
167.1
Yossi: No! Now isn’t that funny, you see… …all of the cards have exposed their faces… except for the shy card, the Jack of Spades!
184.9
Orel: Oh my God! How do you do that?! You’d like to know how I do that?
189.4
Orel: Yes!
189.4
Yossi: Ah ha! It’s a magic trick - I’m not going to tell you! But, it’s up to you guys… to try and find out how I do these magic tricks! They’re all based on math! Want to try?

Now for a surprise! At the end of each week I’m going to perform a magic trick that is based on math. It’s your job to try and find out the secret behind the trick. Post your ideas below! The correct answer will be disclosed in the weekly email…

If you’ve come so far, you probably enjoy the course. Bear with us for next week, where we’ll delve into some specific topics in recreational math. Now, I’ll dive into the comment to see whether anyone found the right explanation for the magic trick…

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This content is taken from Davidson Institute of Science Education at the Weizmann Institute of Science online course
An Introduction to Recreational Math: Fun, Games, and Puzzles
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An Introduction to Recreational Math: Fun, Games, and Puzzles

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