Introduction: Mathemagical Card Trick

How to perform a common magic trick whether you're a magician or a mathematician.

Step 1: Get a Friend

Ask a friend to randomly select a card from a deck of 21 cards. Have them memorize this card and return it to the deck without revealing it to you.
Optional: Have them shuffle the deck themselves!

Step 2: Lay the Cards in 3 Columns

Start by creating three columns of 7 cards each by:
First, lay the top 3 cards in a row from left to right. (picture 1)
Then add a second row on top the first . (picture 2)
Continue adding rows in this manner until each column has 7 cards. (picture 3)

Step 3: Identify the Column

Have the friend select which column their card is in.
Without changing the order of the cards in this column, gather it into your hand face down, followed by the other two columns on top.
Note: The order of cards in the other two columns no longer matters.

Step 4: Again and Again

Repeat Steps 2 and 3 beginning with cards from the top.
Repeat a third time.
After the third time doing this process the card your friend selected will be the last card in the column they chose.
Memorize this card!

Step 5: Blow Their Mind!

Randomly shuffle the cards into a deck. Begin flipping cards over one by one face up until your friend's selected card is revealed. Impress them with your mathemagical knowledge by identifying the card.

Comments

author
freckles201 made it!(author)2014-02-22

Isn't this like the 21/9 card trick?

author
divadancer903 made it!(author)2013-07-28

does this actually work?

author
betainr made it!(author)2012-11-05

very nice...but whats the mathamatic calculation works on it...can u explain..please..?

author
niravdaraniya made it!(author)2012-04-28

Thanks for this magic

author
broper made it!(author)2011-08-22

nice

author
MorNuN made it!(author)2011-08-21

that girl's very pretty :$

I knew this trick from a children magazine I used to read when I was a child

author
valleycrosser made it!(author)2010-05-02

 You can also multiply the piles of cards of 7 up to as many as possible(which is seven,by the way)and it still works. You may have to experement at first to find how many times you need to do steps 2 and3. Good trick too. 

author
MattyNX made it!(author)2010-04-18

Just tried this trick and it's amazing.... love things like this.

author
VampiricPie made it!(author)2010-02-12

It never is in the middle column for me, but it's always the last card in the column it's in, am I doing something wrong?

author
CalicoP made it!(author)2009-05-05

Wow this is really good!

author
numpska made it!(author)2009-03-11

Oh my god, this is awesome

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