For the most part, we do use metric units: distances are in kilometres, weights are in kilograms, and so on. But a few things, like body temperature, body height, and surveying, are still in the old units.
So we needed to buy four boxes of tiles for skirting, each containing four tiles. All tile shops price their tiles "per square foot". But these tiles are "20x20", i.e., 20 inches to a side. So how many square feet are 4 boxes of 4 tiles each? Quick now! Of course, he reached for his calculator, and after several fumbles, got an answer I had obtained with pencil and paper: 44.44 square feet.
Is that the answer? Not exactly: though the shops and the contractors are stuck in British days, the manufacturers have in fact gone metric. So these tiles are not 20 inches to a side, but 500 cm -- half a metre -- to a side. If you account for that, the true answer is about 43.05 square feet. Of course, we didn't think of that in the shop.
Now let's see how that would have worked out if the price were in square metres. How many square metres to a tile? A half squared, that is a quarter. How many tiles to a box? Four. How many square metres to a box? One. How many square metres in N boxes? N. How many pushes of calculator buttons needed to do that? Depends on whom you ask.
When will these people decide that their lives would be simpler if they used the same units the rest of the world (excepting one, but including our former imperial rulers) use -- the same units that the manufacturers use?
Or maybe it's a scam: they call the tiles 20x20, rather than a quarter square metre, to be able to overcharge by about 3%.
Well, that was actually the least of our annoyances in the exercise, but at least the job got done and the result looks fairly good. Could have been better, could have been much worse.
Oh, by the way: according to Wikipedia, there are 1 17/33 links in a foot.