A child prodigy in mathematics, at the age of 17, Neményi won the Hungarian national mathematics competition. Neményi obtained his doctorate in mathematics in Berlin in 1922 and was appointed a lecturer in fluid dynamics at the Technische Hochschule in Charlottenburg (now Technische Universität Berlin). In the early 1930s, he published a textbook on mathematical mechanics that became required reading in German universities. Stripped of his position when the Nazis came to power, he also had to leave Hungary where anti-Semitic laws had been enacted, and found work for a time in Copenhagen.