Even if you haven't personally gotten hit with weblog spam much, it will probably affect you at some point. (I've only gotten a few here and there, so I've been able to manually manage it up to this point.) One of the ways to stop comment spam is to implement a CAPTCHA, a simple test that a human can pass really easily that a computer cannot. One example of the proliferation of CAPTCHAs: often when you sign up for an account somewhere, there are those annoying boxes that have a random string of numbers or letters in an image that you have to replicate in a text field. Well, they're not THAT annoying, since it takes like two seconds to do them. However, they're still evil.

But Ridiculous Fish (or the author behind it, anyway) has implemented the coolest CAPTCHA I've ever seen. Basically, by posting a comment, you have to enter two large numbers into two text fields, and by doing so, you help calculate the value of pi! The author goes through all the mathematics about why this is true (except for the actual evaluation of the infinite product), and it's so fantastically interesting, at least to a math major anyway.


Pi is currently around 3.353177 after 907 submissions, though, so it's not very accurate at this point. I'm also betting that the pairs of numbers given by people aren't actually random, which skew the results a bit. It's probably biased due to the layout of the numeric keypad or on the regular part of the keyboard. (For instance, I notice that my first number almost always starts with a 6 if I "indiscriminately mash" on my numeric keypad.)

But it's pi! How can you not like pi?! (Spam pie, on the other hand, is an awful idea and is gross to even think about. But whatever.)