Prodigies are individuals with exceptional mental abilities. How is it possible that some of these people mentally calculate exponentiations with high accuracy and speed? We examined CP, a mental calculation prodigy, and a control group of 11 normal calculators for moderate mental arithmetic tasks. CP has additionally been tested for exceptionally difficult exponentiations. We hypothesized that, if CP would activate similar brain regions as controls for both moderate and very difficult tasks, his special exceptional abilities could rather be explained by neuroplastic changes as a result of obsessive practice than by unusual mental strategies and/or neurocognitive mechanisms. For very difficult exponentiation tasks, CP showed activation patterns in brain regions adjacent to those, which were activated for moderate task calculation by both CP and control participants. We concluded, therefore, that CP's exceptional calculation performance might rather be based on neuroplastic changes substantially caused by years of daily hours of training combined with excellent working memory capabilities and not on the recruitment of additional brain mechanisms. Furthermore, but considering that only one prodigy was compared with a control group, results of the present study imply that the neural substrate, which is potentially necessary to enhance specific skills dramatically by positively motivated excessive mental training, might be present in every healthy individual. (Contains 1 table and 4 figures.)