There are two known errata as of 1-30-2023.
* In section 11.2.3 we should use the next prime after 26^2+26.  
Thanks to Jennifer Firkins Nordstrom of Linfield University
for pointing this out.
* In the second to last paragraph after Proposition 2.1.4, it says
"there are only b possibilities for r", but using the given notation,
it must be "there are only m possibilities for r".  Thanks to
Caleb Shor of Western New England University for pointing this out.