Set one up when I used a different handle but literally never used it. Thought I had a short ID number but, for reasons I'm not sure of, the piddly scrap of paper I wrote the number down on has always been in a particular place (and has been there for well over a decade), and it was 9 digits.
Must have been thinking of that handle's Slashdot ID. That was 6 digits.
... and technically still is. Wow. The account is apparently still there. Not sure I'm going back there any time soon, but took this opportunity to reset the password just in case.