乙種第4類 丸暗記ノート is an iPhone application developed by Toolbox Co. Ltd. It is a free app that accompanies the book "(増補改訂3版)１０日で受かる！乙種第４類危険物取扱者すい～っと合格" published by Toolbox Co. Ltd. The app aims to provide an easy-to-use digital version of the memorization notes included with the book. The content of the app is aligned with the book, making it a valuable supplementary tool for readers.

The app offers a user-friendly interface that allows readers to conveniently access the memorization notes on their iPhones. It provides a seamless integration with the book, allowing users to enhance their learning experience by accessing the digital notes alongside the book's content. With this app, users can easily review and memorize the important information related to the handling of hazardous materials covered in the book.

Overall,乙種第4類 丸暗記ノート is a useful companion app for readers of "(増補改訂3版)１０日で受かる！乙種第４類危険物取扱者すい～っと合格." It offers a convenient way to access the memorization notes and enhance the learning experience for individuals studying the handling of hazardous materials.