I understand that the order of magnitude is the scale of a value expressed in the metric system. For example, 500 and 900 would be of the same order of magnitude as the both are in the magnitude of 10^2. However in the metric system, there are "gaps" between some of the orders of magnitude. For example, it goes 10^1, 10^2, 10^3, then 10^6. My question- is there any unit of measurement between 10^3 and 10^6? There are two unlisted orders of magnitude between these two, and it just goes from kilo to mega with no listed units or orders of magnitude in between. So there's two orders of magnitude missing. What's the reason? It seems awkward to have kilo of magnitude 3, then skip directly to mega with magnitude 6.