Do I need to read all the previous JLA Books to jump into Book 7 (Tower of Babel)?

I noticed that they have numbered the JLA (Justice League of America) books over at amazon.com. Is it because they continue each other or just to know the order they were published in? In other words, do I need to read everything prior to Book 7 (Tower of Babel) to enjoy/understand JLA Book 7: Tower of Babel?