I read this once and then stored it. There's a stain-like mark on the side, which might come off if you rub it with sandpaper, but I'm afraid to try, so I'm selling it as is. Please consider purchasing if you understand. This book introduces 50 basic mathematical ideas. - Title: 知ってる？人生に必要な数学 50 Mathematical Ideas You really need to know (Do you know? 50 Mathematical Ideas You Really Need to Know for Life) - Publisher: Gijutsu Hyohronsha (Technical Review Company) - Condition: Minor scratches Thank you for looking.