In the gaming industry, "bookmaking" has nothing to do with reading or writing. But it has everything to do with arithmetic!
The people who manage race and sports books for casinos don't just register a person's bet on a horse race or a football game. They are ultimately responsible for setting the "odds" that determine how much the winners will receive for each dollar bet.
These days, computers do most of the calculations, so being comfortable with the appropriate hardware and software is essential. But a thorough knowledge of how bookmaking works is also crucial.
Race and sports book managers must be able to tell at every moment whether the odds on a given event make sense. If they don't, "book" managers must be able to determine if there is a problem and be able to fix it quickly.
If problems are not identified and corrected, the casino could lose a lot of money. As a result, casinos depend on their sports and race book managers to see that "the book" runs smoothly, efficiently, and profitably!