In the clip, Charlie plots the bombing locations on a map and is able to find the "center" of those points, which is the most likely place the bomber would choose as a base of operations. There are many geometric notions of center of a collection of points in the plane. One obvious one is the point which minimizes the sums of distance from that point to all others. Unfortunately, such a point is often difficult or impossible to find explicitly. This is because the distance between two points involves a square roots, which are difficult functions to analyze.