Any point in a volume of space defined by four equidistant points can be located by recording its distance from each of those four points. In this system, then, four numbers locate a point. Each number represents a multiple of the unit assigned to the distance of 1 unit that separates the four points of the framework. If, then, the unit distance is 1 light year, and the universe we wish to describe has a radius of 13.8 light years, four integer numbers not greater than 15 billion will locate any point in that universe to an accuracy of 1 light year. This led me to want to know how many bits are required to represent the decimal number 15 billion.
I briefly considered using a bit of JavaScript to perform the calculation, but I worried it wouldn't work. I recently read about a search engine that is good at answering questions about numbers, but I failed to note the link, so I used Lycos, and asked it "how many bits are required to write the number 15 billion?" I got a list of links, and found a very satisfactory answer on the second page I visited.
