Mystery To Solve From 1973

I remember when we got a new, sequentially numbered stack of bills from the bank, they seemed somehow "special" back then. There was somewhat of a notion that in the future, people may want to have sets of sequential notes. While my grandfather and I never put away a whole stack of 50.00 (a lot more money in those days), we did save some smaller runs of sequential numbers that would sometimes show up in his bill changers.