This workbook is published to reflect the newly revised 2022 curriculum starting in 2024. 1. Ten problems solved with your mind matter more for math skills than a hundred problems solved with your hands. Arithmetic that only teaches calculation methods can build 'computational skill,' but it doesn't necessarily lead to true 'math ability.' Just as calculation has principles and methods, each calculation has its own properties, and there are relationships between different calculations. Children also need to be able to apply calculations and develop number sense through them. To enable multi-dimensional calculation training rather than a one-sided approach, this book presents problems that allow children to think about a single operation from various angles, all designed with a solid mathematical rationale. 2. Only arithmetic that contains real mathematical meaning—not just the four basic operations—can build a strong foundation for elementary, middle, and high school math. Because math is a continuous subject spanning elementary through high school, the concepts formed in elementary school affect learning in middle and high school. Concepts learned in elementary school may seem simple, but since they connect to important concepts in middle and high school, arithmetic learning that highlights their mathematical meaning is essential. This book also lets children experience, at an elementary level, the mathematical rules taught in middle and high school, helping to anchor their overall math learning. 3. Math concepts stick only when children think, solve, and truly feel them. Arithmetic practice that is just calculation from start to finish can bore children and cause them to miss the mathematical meaning behind the calculations. This book creates a multi-dimensional learning structure that helps children understand which mathematical principle underlies each calculation method, connecting calculation practice to genuine understanding of math concepts. In addition, the answer key separately explains why the math concepts in each problem are important and how they connect to middle and high school learning. Contents: 1. Addition of three numbers where two numbers sum to 10 2. Subtraction of three numbers where two numbers differ by 10 3. (Single digit) + (single digit) with carrying 4. (Teen number) - (single digit) with borrowing 5. (Tens) + (single digit), (single digit) + (tens) 6. (Two-digit number) ± (single digit) without carrying or borrowing 7. (Two-digit number) ± (two-digit number) without carrying or borrowing