The divergence of the harmonic series is the source of many counterintuitive conclusions, such as this one:
Given a collection of identical dominoes, it is clearly possible to stack them at the edge of a table so that they hang over the edge of the table without falling. The fun fact is that one can stack them in such a way to make the overhang arbitrarily large, provided there are enough dominoes. 🙂
The Mathist 