This book, “The Buddhivilasini: Commentary of Ganesa Daivajna on the Lilavati of Bhaskaracarya II” is a version of the thesis, for which Dr V. Ramakalyani has been awarded the degree of Doctor of Philosophy by the University of Madras in 2018. Among the published commentaries on Lilavati, Buddhivilasini stands out for its characteristic treatment of the original work as Buddhivilasini contains more than hundred upapattis (Indian proofs) for almost all the rules of Lilavati. In the context of Buddhivilasini, upapatti is either a description of the process, numerical demonstration thereof, verbal explanation, reasoning utilising algebraic rules, proportion, examples or justification.