How many pages does 'The Boys Start the War' have?

According to Amazon.com, on this page: http://www.amazon.com/Boys-Start-War-Girl-Battle/dp/0440418410, this paperback version of the book has 144 pages. Other editions have other amounts... for instance, on the same site, the hardcover version is listed at 133 pages. Different paperbacks could have different sizes as well, and so then the number of pages could get bigger or smaller... the same would be true if they used different fonts or different font sizes.