The main goal of this journal is to popularize mathematics through the electronic publication of original works. The articles it contains are intended to appeal to a wide spectrum of readers, ranging from young people with a general interest in mathematics to professional mathematicians. Articles can be written in any of the languages commonly used in the mathematical community of the country. For the benefit of readers, each article is accompanied by a symbol that indicates the audience to whom is addressed: Readers interested in mathematics. Readers with some mathematical background. Mathematicians. To submit a paper to this journal, please send it to either of the editors Armengol Gasull or Gregori Guasp, preferably electronically to the electronic address of the journal, or by ordinary mail to: Materials Matemàtics Departament de Matemàtiques Universitat Autònoma de Barcelona 08193 Bellaterra (Barcelona) If you want to know each time that a new work is published, please click here to send an e-mail. Published Articles: Volume 2012 Volume 2011  Now also in e-book format!!! Volume 2010 Volume 2009 Volume 2008 Volume 2007 Volume 2006