You are headed back to university, or haven't taken a math class in twenty plus years and the school requires a math course. Or you put off going to college for a few decades. Or you did not do well in any of your math classes during your birth through high school graduation year. The book may not be the best in class, but it is not the worst I have seen. Besides, you get out of any book or tool, generally, what work you put in to it.