The general report of Duel 2015 in Bielsko-Biała can be read in the following pdf file.
Markus Ruprechter, a student from BRG Kepler Graz, who participated at Mathematical Duel 2015 wrote a report of this competition in German.
A travel report in German of Mathematical Duel 2015 was written by Gerda Prach, a student from BRG Kepler Graz, who participated at this competition.
One day of Duel 2015 in Chorzow was the 14.3.2015. This is a very special date for all mathematicians because at 9:26, the date is 3.14.15 9:26 in english notation. These are the first numbers of pi, 3,1415926. So this day was the "pi-day" and there was something special prepared for us. Daniel Horiatakis, a student from BRG Kepler Graz, wrote a report of this special day in German.