Those are interesting. I look but never find. The high light of the few bills I have is a 1935 silver cert. star note. By the way I may have a total of 7 paper notes.
Welcome to CT @Bill Alexander. A true binary would be 1's and 0's, but the paper money world has loosely appointed any two numbers as a binary. I've never heard the term solid binary, but that's not to say it hasn't been used before on eBay as hype for selling a note. Interesting serial number.
The paper money world has also loosely appointed any two numbers beginning with 6 as being an UNC note.
Me neither, but I've heard the term "progressive" for serials like this. The idea is that it's one of the serials you need in order to build a "progressive set" like 77777777 77777772 77777722 77777222 77772222 77722222 77222222 72222222 22222222 Dunno how many people actually collect this way, though.
