Aryabhatiya or Aryabhatiyam, a Sanskrit astronomical treatise, is the magnum opus and only known surviving work of the 5th century Indian mathematician Aryabhata (476–550 CE) who was the first of the major mathematician-astronomers from the classical age of Indian mathematics and Indian astronomy and played an important role in shaping scientific astronomy in India. Based on the parameters used in the text, the philosopher of astronomy Roger Billard estimated that the book was written around 510 CE. The present work ‘The Āryabhatīya of Āryabhata: An Ancient Indian Work on Mathematics and Astronomy translated with notes by W. E. Clark is a preliminary study based on inadequate material. Of several passages no translation has been given or only a tentative translation has been suggested. The present translation will have served its purpose if it succeeds in attracting the attention of Indian scholars to the problem, arousing criticism and encouraging them to make available more adequate manuscript material. Walter Eugene Clark (1881-1960) was the Professor of Sanskrit in Harvard University.