I revisited my Aussie paper notes. I saw that my old $100 has a serial with the prefix ZES. I remember something about Z being a replacement note, then something else about that not being the case on $100s. Can someone help?
Yes, for older paper notes, the star replacements have a star as well as a serial number beginning with Z. However, the star replacement note system was abolished in Australia in the mid-1970's, and the paper $100 was not introduced until 1984. With the star notes no longer requiring the "Z" prefix, that letter was now free for use for the new $100 note (all the other letters having been assigned for use on other denominations). All the paper $100 notes have a Z prefix.
Don't say "infinitely" when you mean "very"; otherwise, you'll have no word left when you want to talk about something really infinite. - C. S. Lewis