## 22 May 2011

### Mathematical card trick

I started learning card tricks to cheer up kids back when I was doing volunteer work in hospitals in the 1960s. Mathematical tricks are the best, because no sleight-of-hand is required. This is not my video; I'm just posting it for future reference.

Explanations of the math are in the Reddit thread.

1. Hi, my wife just showed me the video... watching your "shuffling" at the beginning you can figure out that the random part does not at all change the positions of the aces in the resulting pile. The random set of x cards is on the right pile, the remaining 15-x cards on the middle pile under the next ace. In the end the middle pile goes on the right pile making it exactly the same 15 cards between the two aces that were on the middle pile before - just randomly restacked (only those 15 cards) - the same thing happens with the other random part and the right pile. To puzzle the audience more you do the 4 cards-thing at the end.
Result: Your aces are always on position number 6, 22 and 38. Because of the way you eliminate the open cards, those three cards stay until the end.

J. from Germany

2. I wrote a long comment, then Blogger said "We're sorry, but we're unable to complete your request."

Blogger is incompetent. The programmers behind its commenting system deserve a close encounter with rotting vegetables. Otherwise they would make sure that when that happens, there's a way to recover the comment.

Basically, my comment was a summary of a card trick I invented once, containing both mathematics AND sleight of hand. Let me know if you're interested enough for me to try again in a few hours.

3. I just checked the spam filter; it didn't wind up there.

You can try again, or not, at your discretion. Or perhaps put it in your blog and leave a link here.

4. Let's just say, I took a very well-known mathematical card trick (which in its original form is rather derided by magicians) and elaborated on it by adding some shuffles and other manouvres and also a narrative involving robbed temples and angry gods.

Instructions for the whole routine are online, but on a password-protected page. I'd love to get it recorded on video some day, but I don't really know anyone who's good with a video camera.