I took Calc 2 at my university and borrowed my roommate's book that he bought the year before. It was useless because it was the "preliminary edition". It was

I took Calc 2 at my university and borrowed my roommate's book that he bought the year before. It was useless because it was the "preliminary edition". It was virtually the same book except all the exercises were in customary US units instead of metric. Can you imagine, publishing a math textbook in 1995 in customary units? All of my high school books had been metric and were a decade old. There could only be one reason to do so -- to require the next group of students to buy the new book.