This California college has a no-frills $602$-page textbook
available for free PDF download:
College of the Redwoods Mathematics Prealgebra Textbook. 2012-13. (PublisherLink).
There was a free website for download in 2015, but apparently no more. Before its demise, I browsed through book.
What "fluff" the textbook authors include is hardly fluff; rather, educational:
Note the sum $$ \frac{1}{2} + \frac{1}{4} + \frac{1}{8} + \frac{1}{16} + \frac{1}{32} + \frac{1}{64} = \frac{63}{64} $$ is missing $\frac{1}{64}$ of Horus's eye.