@sophieschmieg @mhoye @futurebird It's an artifact of when some silly English git decided that the mile, which the Romans pegged at a sort-of-sensible "thousand paces" at 5 feet per "pace", needed to be an exact integer number of furlongs.
What is a fscking furlong? An originally not-too-terrible agricultural unit, representing a more-or-less typical length of plowed field. Unfortunately, the official "furlong" was 220 yards or 660 feet, which is not only why there is a cursed factor of 11 in things, it's why the English (and hence US) mile is 5280 feet (=8x660) instead of 5000.
It gets worse, and I'm not going to go into it here (the attached Wikipedia article covers it better), but the furlong itself was once more "even" (600 feet), and it *also* got contorted into something more awkward because of an underlying unit re-definition.