Introduction
Structure of this book
Study in this order

| In-depth study by unit |
Unit 1 Multiplication
Unit 2 Division
Unit 4 Fractions
Unit 5: Loading and Weight

| In-depth Comprehensive |
1 set
2 sets
3 sets
4 sets
5 sets

| Skills Diagnostic Test |

A new structure that helps transition from concept and application textbooks to advanced courses.
It consists of only good problems worth investing time and effort into solving.
There are many meaningful problems in terms of their connection to secondary mathematics, and many good problems that require examination of the solving process.
However, the preceding concepts only include those that are meaningful at this stage.
Since many children give up on advanced textbooks that are too difficult compared to the applied textbooks, we have appropriately adjusted the difficulty level to ensure a smooth transition from applied to advanced textbooks while still preserving the spirit of solving difficult problems on one's own.

Step-by-step hint-style answer sheets to help children solve problems on their own
The most important features of this book are the answers and explanations.
Before you see the full solution, we've structured it so that you'll first get hints up to three levels deep.
The purpose of deepening is to solve problems 'by yourself'.
If you immediately look at the answer sheet and memorize the solution because you are having trouble solving it, it will have no effect at all on solving more advanced problems.
As you gain experience solving problems on your own, your problem-solving skills will also improve.

Concept confirmation, in-depth learning, and skill check all in one place
This book first reviews the basic concepts for each unit.
And by solving advanced problems, you will learn various types of advanced problems.
Then, you will solve an in-depth comprehensive test in the form of a mock exam, and at the very end, you will check your skills with a 'skill diagnostic test' to finish.
Therefore, if you solve this book, it will have the effect of summarizing one semester's worth of material, from the textbook to the advanced level.
This book is designed to help students who have mastered basic concepts and applied materials to easily proceed with advanced learning for the first time.
However, it is also recommended for students who want to skip the application and challenge themselves with advanced concepts after mastering the concept textbook.
Because if you invest two hours a week, you can conquer a book within a semester.
It is also recommended for students who need to deepen their knowledge but are short on time.