I don't think there's a more delightful way to enjoy and learn mathematics than solving interesting problems. Here are links to some I like best:
I welcome your comments, criticisms, and most of all, problems (and solutions!). Feel free to contact me if you have anything to offer.
Dr. C.S.Yogananda, member of the Olympiad Cell, is preparing "The Joy of Discovery", a book of essays contributed by olympiad students. Here are my contributions:
I would appreciate your feedback.