This is one of the few books about how to use an abacus around. Even though there aren't that many books out there, Kojima does a very good job of explaining how to use the abacus, in a step by step manner. The book starts off with a brief history of the abacus then proceeds to how to use it for addition, subtraction, multiplication and then division. The book also goes into cube roots! The book also has some simple tests after each chapter and at the end of the book to see how much you have improved. All in all the book is very well written and if you have any interest in the abacus, this is a good book to have.