Numbers, by themselves, are cold most of the times. And it's hard to get an idea of what they really mean. I remember Xoan G., my first great teacher on this profession, explaining us at La Voz de Galicia an idea: if you say that something have the same area than 200 soccer fields, for me it's just the same that if you tell that is the same than 20 or 2000, the comparison goes beyond human mind (when reading a newspaper) and identifies the amonut as "a lot", with no further complications.
When we really want to explain a really big amount of things, we have two good ways: compare it with just one thing or visualize it as big as it is.
This time, the blog The Big Picture published on Boston.com showed the visualiazation of the 1.400.000 deaths resulting from Khmer Rouge policies in Cambodia. We could compare that number with the whole population of San Antonio, as an example. But they did this (Click on the image to see it full size):