The Aryabhatiya of Aryabhata is of great work in the annals of the history of Indian mathematics and astronomy. This volume is expected to give a complete translation (with notes) of the Aryabhatiya with references to some of the most important parallel passages. It is a brief descriptive work intended to supplement matters and processes which are generally known and agreed upon to give only the most distinctive features of Aryabhata's own system. Many common places and many simple processes are taken for granted. The book vividly addresses topics such as dasagitika, ganitapada, kalakriya and gola in much details. Withstanding many a criticism from people like Brahmagupta on the theories of Aryabhata, this volume through the introductory chapter contends that the Aryabhatiya, on the whole, is quite genuine. It presents Aryabhata as an innovator, thus his difference from Smrti or tradition in his approach to many astronomical matters is fully justified. It also discusses a serious internal discrepancy in the Aryabhatiya about the stationary and revolutionary nature of earth. This book helps in introducing Aryabhata and the quintessential of Aryabhatiya to the mathematicians and astronomers of the new generations, for whom the original language Sanskrit and the old processes might be unknown. Walter Eugene Clark (8 September 1881 - 30 September (1960), was an American philologist. He was the second Wales Professor of Sanskrit at Harvard University and the editor of the Harvard Oriental Series, vols. 38-44. He made ready this volume just one year before his demise.