%A J?rgen Bredenkamp %J Wissenschaft und Verantwortung. Festschrift f?r Karl Josef Klauer %T Kognitionspsychologische Untersuchungen eines Rechenk?nstlers %X A detailed analysis of the processes of a mental calculator (Gert Mittring) is given in this paper. It shows that seemingly exceptional tasks (e.g., mentally extracting the 137. root from a number with thousand figures within less than 20 seconds) can be described in the frame of conventional cognitive processes. %K Rechenk?nstler, mental calculator, Gert Mittring %E Hubert Feger %D 1990 %I Hogrefe, G?ttingen %L cogprints6620