NicholasW asks: where on earth did the hash # key come from?

I'm not sure it was on old typewriter keyboards. I have at home an old typewriter that brings up images of archie scurrying about the keys. I'll check it out.

I think the computer keyboard owes more to the teletype than to the typewriter. The 1 key did not exist on the typewriter keyboard; we made do with a lowercase l. It was necessary on the teletype to avoid misunderstanding in context poor situations. The # key was undoubtedly necessary for similar reasons.