Named the world champions in solving mathematical problems in mind

Completed in Germany on the World Championships in solving mathematical problems in mind won two students. They were Martin Drees from Cadolzburg (12 years) and Andreas Berger of Jena (17 years old).
 
Tournament participants were asked to solve a juvenile 45 pages with various mathematical problems, which included the multiplication of fractions, multiplication and division, as well as the extraction of roots. The tournament was attended by 35 young people from 8 different countries.

Andreas Berger, who by the way is noted for 3-time world champion, was able to correctly solve 80% of all samples as well as set the record for the fastest root extraction - in just 14 seconds, he was able to extract the mind root of 7533198 436.

Also note that one of the organizers of the tournament included eight-time champion on the challenges in mind Mittring Gert, who last set Guinness record - he managed just 13, 3 seconds to remove the root in the mind of the 13th degree of the 100-digit number.