Well what I have here is as follows:
TIME-LIFE Books UNDERSTANDING COMPUTERS (C) 1987
[snip]
There does not seem to be a numbering system such as a
volume number
anywhere within or outside the books (such as on the spine).
That is because there is no number system, these were sold on a "preview"
basis, get the first one for $1.99 and they send you one once a month that
you can "keep" for only $9.99+shipping. There are lots of Time-Life series
like this.
--Chuck