A spine marked 47 can make a book look like the middle of a very long story. The number may instead identify its place in a publisher’s series containing unrelated works. Buying the preceding number will not necessarily supply a missing chapter.
Start with the title page, series page and contents. A work divided into volumes should identify the particular volume and its relationship to the whole. A publisher’s series may group books by subject, format or editorial programme without making them one continuous text.
Write down two separate descriptions
Record the work’s title and volume information on one line. Put the publisher’s series name and number on another. This keeps a bookseller’s short listing from collapsing two different sequences into “volume 47”.
For an invented example, a book called Coastal Letters, Volume II might also be number 47 in a series called Studies in Regional History. The preceding volume of the letters would be relevant to completing that work; number 46 in the publisher’s series might concern another subject entirely.
Check the author or editor, publication details and ISBN where present. Reissues can move a work into a different series, and older books may use numbering conventions that need a library catalogue or the publisher’s records to clarify.
Ask for the page that settles the question
When buying remotely, request an image of the relevant title or series page if the description is ambiguous. A photograph of the spine alone may not distinguish the two numbers.
If you are completing a set, list the actual contents you want rather than filling every numerical gap in a shelf sequence. This small distinction saves money and produces a clearer catalogue: it tells the next reader both what the book contains and how the publisher presented it.