## Monday, October 02, 2006

### How many links in a foot?

Just got over with tiling the house. Plenty to say about that, and we've been saying it on email, so here I'll restrict myself to just one of my numerous pet peeves, that extends beyond this project: why, nearly 60 years after the sun set on the British empire, are we still stuck with imperial units in India?

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.

Tabula Rasa said...

very mindsport / martin gardner feel to this. intentional?

Rahul said...

Not intentional. It was written as a rant...

But now that you mention it, I believe I read a rant by Isaac Asimov long ago on the system that the US (and, at the time, Britain) refuses to give up. It was filled with nuggets like a letter from an elderly British gentleman who said "a litre of beer is too much and half a litre is too little, but a pint, ah, that's just right", which Asimov clarified for confused American readers: a half-litre is larger than an American pint, but it is smaller than a British pint.

Asimov regretted that the US founding fathers, who had the foresight to adopt decimal currency, did not also adopt decimal units of measurement. But it seems to me that Americans don't even understand decimal currency. I was confused by petrol prices like "\$1.95 4/10" until someone (you, I think, actually) told me it means \$1.954. And until 2001, stock quotes were in units of 1/16 of a dollar.

Tabula Rasa said...

yup, twas me.