This one has been around for nearly 100 years, but I just came across it today. Here's how it goes... There's a column of soldiers a mile long walking along at a uniform and constant pace. A messenger is sent from the front of the column to deliver a message to the rear of the column and immediately return to the front. The messenger travels at a constant pace, and upon the messenger's return to the front, the column has covered it's own length. How far does the messenger travel? I have the answer (along with the way I solved it...probably are multiple ways), and I'll post it a little later on.