Three children, Tom, Hannah, and Shadowchild, who represents the reader, are made to guess, using the concept of binary logic, the color of the hats on their heads.

• ISBN: 9780399212123
• Author: Nozaki, Akihiro
• Illustrator: Anno, Mitsumasa
• Published: 1985 , Philomel
• Themes: Mathematics
• Descriptors: Asia, Fiction, Japan, Picture Book, Primary (ages 6-9)
• No. of pages: 41