A
week and a
half is an odd unit of
measurement of
time. Since a week is
seven days, a week and a half is actually ten and a half days, but what takes precisely that amount of time? So in fact when someone says they're in town for a week and a half, or the festival runs a week and a half, they really mean something close to that, but not quite exactly that. In actuality if someone trots out this approximation, they could mean anything from nine to twelve days.
If it's just
eight days we're talking about, that's pretty much a week. If its thirteen, that's pretty much two weeks. Heck, even twelve days is close enough to two weeks to throw out there if you're going to be in town just that long (and if you're talking about how long you'll be on vacation from work, missing ten days of work (with a weekend in between) is two weeks, so it would probably be a week and a half to miss seven or eight. Naturally, all of this would be tossed aside if a week were an even number, especially if it were the
decimal sort of ten-day period that
paralleled the
metric system. But, oddly enough, despite the
European penchant for going by
units of
ten and
multiples of ten, there's never been a serious
movement even to divide days up in decimal block. If there had been, maybe a week and a half would be a rough patch between thirteen and seventeen days.