Hans Eberstark is a great Austrian linguist, translator, and mental calculator. There was a very interesting profile on him in the October 1993 issue of Atlantic Monthly.

Eberstark would often lecture on language and translation in Europe, and was famous for asking someone whose first language was a small local dialect of German (particularly Swiss-German, of which there are countless dialects) to speak with him (during the lecture), after a couple minutes of which Eberstark would suddenly start speaking fluently in that dialect.

He spent some of his early years in a ghetto with other displaced people from all over Europe. It was there that he was exposed to many different languages.

He also is known for having once recited 11,944 successive digits of the mathematical quantity of pi (3.14159 . . .) from memory. During an earlier attempt he had intended on reciting roughly half that many but had made a mistake. He was angry with himself for the mistake so he memorized even more.