This is a complete set of 5 books; we do not sell them individually. Please note that all pages have been cut, and the books are in pieces, so they are listed as damaged. There are no markings. The basic level is interesting; children who like math will solve the problems quickly. The advanced level is, as expected, advanced and moderately difficult. It's good for children who want to solve challenging problems. This is a problem book for elementary school students designed to cultivate thinking skills, including standard and advanced editions. - Title: Thinking Skills Expanding Workbook for Elementary School Students - Series Name: Z-kai - Edition: Standard Edition - Edition: Advanced Edition - Target Audience: Elementary School Students Thank you for viewing.