Author: Ryo Honmaru It is said that the brain's intuition, processing power, memory, and concentration peak around the age of 18 and then decline. However, it is known that solving various arithmetic and mathematical problems can slow down that decline, or even improve these abilities. Therefore, in this book, we will train your brainpower by solving quiz-like problems! The genres are "Angles," "Area & Length," "Net Diagrams," "Volume," "Sequences," "Missing Digit Problems and Magic Squares," and "Statistical Quizzes," spanning seven fields. Let's try challenging problems from your favorite fields! Chapter 1 Angles Chapter 2 Area & Length Chapter 3 Net Diagrams Chapter 4 Volume Chapter 5 Sequences Chapter 6 Missing Digit Problems and Magic Squares Chapter 7 Statistical Quizzes ★Column