Sales Rank at Amazon (whatever it means)

I don't understand how Amazon sales rank works when it comes to book sales, except that a lower numer on the "sales rank" means more sales. I admit I'm a "numbers nut" and I could probably watch these numbers all day left to my own volition. But from what I have read, I doubt the Amazon sales rank really means much at all.

I learned that if you bought a lot of books at once, your sales rank would plummet significantly. In fact, I read that if you bought 1,000 books in a single day, you might fool Amazon and become an Amazon bestseller! Trust me, I'm not planning on doing that. Of course, it would be amusing to see this book hit the bestseller list - that is, until I have to sell all 1,000 books. For whatever it is worth, though, I checked a few days ago, and my Amazon sales rank was in the 40,000s, which is actually pretty good, considering there are more than 100,000 books produced each year. My rank has generally hovered between 40,000 and 260,000 in the past week, a big range indeed. I've seen other sinus self-help books such as The Sinus Cure and Sinus Relief Now in this range as well, although I think Sinus Relief Now has been even lower than 40,000 at times and it has been out since last December. Here are the numbers (although they are probably creeping much higher and in the 6 digits as I write this; I gotta keep this number low to prevent acid reflux! (joke):

Product Details
· Paperback: 236 pages
· Publisher: Cold Tree Press (August 17, 2007)
· Language: English
· ISBN-10: 1583851976
· ISBN-13: 978-1583851975
· Product Dimensions: 8.5 x 5.5 x 0.5 inches
· Shipping Weight: 10.7 ounces (View shipping rates and policies)
· Average Customer Review: based on 2 reviews. (Write a review.) Amazon.com Sales Rank: #40,736 in Books (See Bestsellers in Books)