Description Sangwigwon Yeonsan 960 approaches number and arithmetic learning—the starting point of mathematics and an essential tool across all areas of math—with a new philosophy and methodology. Through task-based arithmetic problems combined with a variety of situations, processes, and approaches, this workbook not only builds solid computation skills but also develops higher-level mathematical thinking. Sangwigwon Yeonsan 960 will be a great support for children who get bored or tired of simple repetitive arithmetic drills, children who need creative-thinking arithmetic practice beyond the basics, children working on advanced application of school curriculum, children who need to think through math rather than solve problems mechanically, children who want to build a strong foundation rather than rush into excessive advanced study, children preparing step-by-step from an early age for gifted education programs, olympiads, or specialized middle/high schools, and every child who loves math and wants to excel at it. Table of Contents 041~080 Addition and Subtraction (1) Issue 1: Decomposing and Composing Numbers Issue 2: Addition Issue 3: Subtraction Issue 4: Addition and Subtraction Answer Key