The Rubik Cube was invented by Erno Rubik (b.1944) in Budapest, Hungary in 1974. Rubik was a lecturer in interior design and had an interest in geometry and in the study of 3D forms. He began exploring the idea of a puzzle that was self-contained in one piece. By 1978 the Rubik Cube was circulating in the playgrounds of Budapest, but it was not until 1980 that the Cube made its debut in the rest of the world. Between 1980 and 1982 it is estimated that more than 100 million Rubik Cubes were sold.