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!

Comments

[betainr]

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

[niravdaraniya]

Thanks for this magic

[broper]

nice

[MorNuN]

that girl's very pretty :$

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

[valleycrosser]

 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. 

[MattyNX]

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

[VampiricPie]

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?

[CalicoP]

Wow this is really good!

[numpska]

Oh my god, this is awesome