Sherlock Holmes is about to celebrate his 121st birthday this Christmas. Since Arthur Conan Doyle first created the detective in 1887, Sherlock Holmes has been paraded on the big screen, parodied, dissected, but most of all beloved by millions. There are dozens of official fan societies and countless offshoots. So there have to be some loyal mental_floss readers out there who can don their deerstalker hats and solve this one in no time flat. After all, it's elementary.