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-solving arithmetic problems that combine a variety of situations, processes, and methods, this workbook not only builds computational skill but also develops higher-level mathematical thinking. Sangwigwon Yeonsan 960 will be a great help for children who find simple repetitive arithmetic drills boring or tedious, children who need creative-thinking arithmetic practice beyond the basics, children aiming to deepen and apply their curriculum knowledge, children who need to think through problems rather than solve them mechanically, children who want to build a solid foundation rather than rush into excessive advanced study, children preparing step by step from an early grade for gifted education programs, olympiads, and special-purpose middle/high schools, and indeed any child who loves math and wants to excel at it. [Book Composition] 6 books for Level P, 4 books each for Levels A–D, 22 books in total D1: 961–1020, Multiplication and Division D2: 1021–1080, Mixed Calculations D3: 1081–1140, Addition and Subtraction of Fractions D4: 1141–1200, Addition and Subtraction of Decimals [Recommended Grade] An essential thinking-skills arithmetic workbook for advanced elementary 4th grade students Table of Contents D4 1141–1200: Addition and Subtraction of Decimals Issue 1: Two-Digit and Three-Digit Decimal Numbers Issue 2: Addition of Decimals Issue 3: Subtraction of Decimals Issue 4: Applications of Decimal Addition and Subtraction Answer Key