I’ve done another maths video! If you missed it earlier this week, here’s a nice mathematical card trick I learned recently on a trip to Finland. Enjoy!

# You're reading: Posts Tagged: card trick

### All Squared, Number 7: Card Magic (Colm Mulcahy part 1)

Colm Mulcahy is an original Aperiodical contributor (Aperiodicontributor?) and friend of the site. He’s spent the last year and a bit writing his new book, *Mathematical Card Magic: Fifty-Two New Effects*. It came out a few weeks ago, so we thought it was a good opportunity to talk to him and find out just what’s so great about mathematical magic tricks.

Actually, we had that thought quite a while ago and if we’d been the least bit organised this podcast would’ve come out the same day as the book. As it happened, we first arranged to talk to Colm back in May, and then it took literally three months before we actually managed to record the interview.

… And then it took us three weeks to edit it up and upload it. Sorry!

Because Colm had so much interesting stuff to say, we’ve split the interview into two parts. In this first half we talk about the book and mathematical card magic; in the second part, out next week, we talk about Martin Gardner and the Celebration of Mind.

*Mathematical Card Magic: Fifty-Two New Effects* is published by CRC Press, priced £19.99/$29.95.

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### David’s de Bruijn sequence card trick

A few days ago, my friend David asked me if I could help him with a card trick. I said I could, hence this post. I managed to pin David down in front of my camera long enough for him to demonstrate the trick; a full explanation follows this video:

### The Odds Gods smile on birthday/card matches

The classic birthday problem asks how many people are required to ensure a greater than 50% chance of having at least one birthday match, meaning that two or more people share a birthday. The surprisingly small answer, assuming that all birthdays are equally likely and ignoring leap years like 2012, is 23 people.