These number systems are created by marketers. Their sense of reality differs from that of the universe itself (for example, mathematics is completely arbitrary for 610 can come after 950). Trying to think like they think is bound to cause heads to spontaneously explode.

More realistically, they want numbers to convey a particular image. The 950 likely had the biggest number because it was a more powerful machine. If Apple wanted to sell an 700 with AppleShare for 3/4ths the price of a 950, they would probably call it a 910 simply because it sounds like a similar class of machine.