28 ms·

See also Project Euler http://projecteuler.net/ http://projecteuler.net/ . Maybe you can use these as advanced captchas?

• sz 16y ago
  Take the one thing a computer can do better than humans and use it as a captcha? Huh?
  • xfs 16y ago
    For Project Euler, they are all textual questions and require reasoning rather than mere calculation.