Sangwiquan Yeonsan 960 approaches the essential foundation of math—number and calculation learning—with a new philosophy and methodology. Through task-solving style number and calculation problems that combine diverse situations, processes, and methods, this series not only perfects calculation skills but also builds higher-level mathematical thinking. Sangwiquan Yeonsan 960 will be a great support for children who get bored with simple repetitive calculation practice, children who need creative thinking-based calculation learning beyond the basics, children preparing for advanced curriculum applications, children who need to think through math rather than solve problems mechanically, children who want to build a solid foundation rather than rush into excessive advanced learning, children steadily preparing from an early grade for gifted education programs, math olympiads, or specialized schools, and indeed any child who loves math and wants to excel at it. [Book Composition] 6 books in the P level, 4 books each in levels A–D, 22 books total B1 (481–540): Addition and subtraction of two-digit and one-digit numbers B2 (541–600): Addition and subtraction of three-digit/two-digit numbers B3 (601–660): Addition and subtraction of three-digit numbers B4 (661–720): Multiplication tables [Recommended Grade] An essential thinking-skills calculation workbook for top-performing 2nd grade elementary students [Table of Contents] B1 (481–540): Addition and Subtraction of Two-Digit and One-Digit Numbers Unit 1: Addition of two-digit and one-digit numbers Unit 2: Subtraction of two-digit and one-digit numbers Unit 3: Relationship between addition and subtraction Unit 4: Calculations with three numbers Answer Key