Strategies for retaining vast amounts of information for the UPSC exam include active recall, spaced repetition, and creating concise notes. Active recall involves testing oneself on learned material, which strengthens memory retention. Spaced repetition combines reviewing information at increasing intervals, ensuring long-term retention. Creating concise notes helps distill information to its essential points, making it easier to digest. Utilizing visual aids and mind maps can also enhance memory by linking concepts. Finally, maintaining a balanced study routine while ensuring regular breaks fosters a more effective learning environment, leading to better retention and recall during examinations.