Resumen de Gergonne's Card Trick, Positional Notation, and Radix Sort

Ethan D. Bolker

• Gergonne�s three pile card trick has been a favorite of mathematicians for nearly two centuries. This new exposition uses the radix sorting algorithm well known to computer scientists to explain why the trick works, and to explore generalizations. The presentation suggests strategies for introducing the trick and base three arithmetic to elementary school students.