A CAPTCHA is one of those computer challenge tests to make sure that you are actually human. Like when they make you rewrite a bunch of random letters and numbers that are next to impossible to read.
These guys have the wrong idea we think. Mixing in calculus with a CAPTCHA is sure to turn away a lot of users. — Andrew Dobrow
not bad, I did it just now:
look at the picture: http://img262.imageshack.us/img262/2792/aaaot0.jpg