- Title: Jack 21 Advanced Math Vol. 3 - Condition: New, Unused - Year of Purchase: 2025 - Number of Books: Set of 2 - Answer Key & Explanations: Included Thank you for viewing. I purchased this while attending Waseda Academy's selective class (SK class), but I am selling it because I never had the opportunity to use it. It was stored on a bookshelf, but it appears to be in very good condition. The content is of a very high level, aimed at the most difficult schools (Waseda, Keio, Kaisei, National Affiliated Schools, etc.) Recommended for those attending Waseda Academy who want to save on textbook costs and those who want to solve difficult problems.