Essential and Advanced Problem Solving Guide for Top Grade 1

1.
[Concept] Only the core concepts and practical concepts needed for problem solving are included at the beginning!
2.
[Problem] Build your top-tier skills with high-hit rate STEP-based problems, and master the easy-to-mistake CSAT-type problems by solving modified problems once more!
3.
[Answer] Detailed explanations are provided, including various solutions, strategies, and concept notes, secret notes, and ideas for solving difficult problems!