h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I haven't read the whole page, but some of the math here is incorrect. In the first part of the combinatorics section, it talks about how many ways there are to pick r items out of a bag of n items where order doesn't matter. They say that there are n! ways, which is not true. If order doesn't matter, divide by the number of permutations of the n items you pick, n!, to get n!/n!=1 way to take n items out of n items where the order doesn't matter. Which makes sense. So if you're actually trying to understand this stuff, go to a different website.