There are some notes written in it. The answers are easier to understand than any other problem book, and after studying it two or three times, I almost mastered it perfectly, so I bought this series. The regular price is also cheap, really!!! I recommend it. Please forgive the notes. Supervised by The Mathematics Certification Institute of Japan Pass! Mathematics Certification Level 2 - Step-by-step preparation to build your ability to pass! The Mathematics Certification Institute of Japan >> 2nd Grade Includes a mock exam that you can cut out and use! (Actual Size) Separate answer booklet for easy checking