Card Colm

Colm with a crown'

Colm Mulcahy is Professor of Mathematics at Spelman College, Atlanta, GA, where he served as chair of the department 2003-06. He spent the academic years 2013-2015 on leave in the DC area. He's is always reachable on email. His writing has been translated into Korean, Japanese, Mandarin, Cantonese, Polish, French and Spanish.

Upcoming presentations & latest articles.


Scientific American         Card Colm           Huffington Post           Aperiodical
George Boole Song & long video (Maths Week Ireland, 8 mins), 2 Nov 2015:

George Boole Song & long short video (Maths Week Ireland, 6 mins), 26 Oct 2015:

Martin Gardner 101 (Google Tech Talk, 53 mins), 30 Jul 2015:

Martin Gardner 1914-2010 (G4G, 9 mins), 21 Oct 2014:

Interview about book (3 mins), 13 Aug 2013:


MathDay, Oklahoma Univ at Norman, OK, 3pm, Thu 19 Nov

Karcher Colloquium, Oklahoma Univ at Norman, OK, 4pm, Fri 20 Nov

JMM, Seattle, WA, Wed 6 Jan


        The Best Writing on Mathematics 2015 (Princeton University Press, Dec 2015)

        George Boole, One of the Great Unsung Architects of Today's World, Is Unsung No More (Huffington Post, Nov 2015)

        The Bicentennial of George Boole, the Man Who Laid the Foundations of the Digital Age (Scientific American, Nov 2015)

        The Mathematical Surprises of Triangles, Squares and Pentagons (Scientific American, Oct 2015)

        Martin Gardner 1914 2010—The Best Friend Mathematics Ever Had (YouTube, Oct 2014-2015)

        The Search for the Mathematically Optimal Pack of Cigarettes (Huffington Post, Oct 2015), also 학자들이 수학적으로 완벽하게 담배를 쌓기 위해 노력하는 이유 (in Korean)

        Given any Delta, there exists Epsilon (Aperiodical, Aug 2015)

        How to Get to the Fourth Dimension (Scientific American, Jul 2015)

        MacTutor History of Mathematics website creators honoured by LMS (Aperiodical, Jul 2015)

        John H. Conway: Genius at Play (Huffington Post, Jul 2015)

        Ingenious Mary: Innovative Irish Science Journalist Leaves a Formidable STEM Legacy (Huffington Post, Jun 2015)

        Myles Away From Mathematics, Magic and Mystery (Huffington Post, May 2015)

        Inteview about George Boole etc (GeorgeBoole200 newsletter, Apr 2015)

        John Conway Reminiscences about Dr. Matrix and Bourbaki (Scientific American, Apr 2015)

        Eight Easy Pieces (you can touch but don’t look) (Aperiodical, Mar 2015)

        Mathematical (and Poetic) Offerings From the Land of Saints and Scholars (Huffington Post, Mar 2015)

        How Many Digits of Pi Do You Really Need to Know? (Scientific American, Mar 2015)

        St Rose's (Belfast, Mar 2015)

        Mathemagic with Cards video (Derby, Feb 2015)

        The Joe Duffy Show (Dundalk FM, 18 Feb 2015, 24 mins)

        MAA's Math Horizons (Mathematical Card Magic: Fifty-Two New Effects book review by Rob Eby, Vol 22, No 2, page 28, Nov 2014)

        MAA's Math Horizons ("Thee Cards Suffice" by Colm Mulcahy, Vol 22, No 2, pages 22–25, Nov 2014)

        MAA's Math Horizons ("Undiluted Hocus-Pocus" review and "The Top 10 Things Every Mathematics Student Should Know about Martin Gardner" by Colm Mulcahy, Vol 22, No 1, pages 24–25, Sep 2014)

        "Let the Games Continue" (Sci Am, co-authored with Dana Richards)

        "Math Games of Martin Gardner Still Spur Innovation" (Sci Am)

        "How Well Do You Know Martin Gardner?" (Sci Am)

        "You Don't Have to Be a Genius to Work at Subway..." (Huffington Post)

        NCTM Mathematics Teacher (pages 194-199, with Al Goetz)

        UCD Connections 2014–2015 (page 73)

        Numbers Game

        A Month of Math, Magic and Mystery (Sci Am)

        Google preview of book


        75 second TV clip


36 mins MAA Google Connected Classroom Hangout on Mathematical Magic with Cards, Apr 2014
(re: Mathematics Awareness Month, Day 3)

6 mins video by Chris Morgan of Ice Cream Trick, Oct 2013
(from Celebration of Mind resources)


A Month of Math, Magic and Mystery (Scientific American)
16 Apr 2014

Math’s Best Friend, Martin Gardner (Scientific American)
29 Oct 2013

The Magic of Math (American Univ)
25 Oct 2013

Martin Gardner–The Best Friend Mathematics Ever Had (Huff Post)
20 Oct 2013

All Squared, Number 8 (Aperiodical)
6 Oct 2013

All Squared, Number 7 (Aperiodical)
29 Sep 2013

Inspired by Math (Wild About Math)
21 Sep 2013

Let the Mathemagic Begin (Math Tango)
15 Sep 2013

Spelman’s Own ‘Mathemagician’ (Inside Spelman)
5 Sep 2013


Mathematical Card Magic: Fifty-Two New Effects, foreword by Max Maven
(AK Peters/CRC Press, 380 pages, 128 illustrations, Aug 2013)

cover art of 'Mathematical Card Magic, fifty two new effects'

"Filled with many original ideas that will keep mathematicians and magicians busy for a very long time" — Arthur Benjamin

"A lot of fun. It's clever, instructive, and clear. Learn some tricks. Learn some math. Impress your friends." — John Allen Paulos

"A stimulating collection of novel card magic tricks that .... form a wonderful introduction to important ideas in combinatorics" — Ronald Graham

"A must for your magic library" — Lennart Green


With the late Martin Gardner, in Oklahoma, Mar 2007. The famed writer was a sweet, unassuming and generous man. He played a significant role in enriching the intellectual climate of a nation during the space race era, turning tens of thousands of people on to the joys of creative thinking. In a sense, he did for mathematics what Julia Child did for French cooking. His legacy is celebrated every Oct with Celebration of Mind parties worldwide.


With Ethan Brown, in NYC, Aug 2013, at the first MOVES conference at the groundbreaking Museum of Math. Though he's only starting 9th grade, Ethan is already an energetic blogger, and a protégé of Art Benjamin. He's a total whiz at magic square completion and can do amazing mental arithmetic feats.


With Ron Graham and Persi Diaconis, in San Diego, Jan 2013, at a book signing for their beautiful and inspirational Magical Mathematics: The Mathematical Ideas that Animate Great Magic Tricks (Princeton University Press, 2011) deservedly won the 2013 2013 Euler Book Prize. The wonderful mathematics and magic in that tome is much more sophisticated than that found in Mathematical Card Magic: Fifty-Two New Effects.

(All photos on this and related webpages are copyrighted and may not be used without permission.)
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