One by one, ten children move from their old house into their new house with all their possessions. Die-cut windows reveal the interiors of the houses and the book can also be read from back to front.

"Superbly demonstrating the conception of factorials in mathematics, the text and pictures combine to present a lesson in a palatable form as well as the pleasure of looking at pictures that only Mitsumasa Anno could invent." — Publishers Weekly"The book moves logically and elegantly from the concrete to the abstract. Once made clear, the concept is unforgettable, but the book entices the reader to return for further appreciation of the artistry with which it was designed." — The Horn Book "If you want a book that does a good selling job on the factorial concept, this one works." — School Library Journal

The reader, with the help of two children, Tom and Hannah, two white hats, and three red hats learns about logic

A wolf's attempt to figure out in which of five houses he is most likely to find one of three little pigs introduces such mathematical concepts as combinatorial analysis, permutations, and probabilities.

数学の本は人気がない。でもこれはとっつきやすく美しく、楽しく、ズッコケているようで鋭い観察に溢れている数学の本である。森さんと安野さん、二人の「数学者」の作った、事典風オール挿絵入り数学読みもの。