[jwecker]

I guess the real issue is which units get names. Yes, you can do with 12cm exactly what you can do with 12in- but the latter gets its own named unit. The Imperial system has a preference for scaling its units by some slightly more practical number of sub-units- 12, 60, etc. I can imagine someone saying, for example, "why name 1000 centimeters as another unit? Can't I say 'thousands' using the same number of syllables? What's worth naming a different unit is 240cm since that's used a lot with timber..."

Someone strictly advocating the metric system would say "that's the point, kilo is another way of saying 1000 no matter where you live in the world or what you're measuring. Feel free to call 240cm a 'frob' if you like, but please, only do so in private- don't order 14 frobs of lumber, order 33.6 meters." (edit: which is a perfectly valid point. It's the slow accumulation of frobs that made the imperial system untenable. We trade a little bit of efficiency at a local level for greater global efficiency when we adopt metric.)

[TheMiller]

Actually, I can remember at least one commonly used alternative name from my time in a German-speaking country. The term "Pfund" (literally, pound) was frequently used to refer to a half-kilogram. I remember it being particularly used in reference to a loaf of bread, by both bakers and customers. (That was a long time ago, don't know if it's still common.)

[eru]

Still common in Germany.

[phaemon]

There's really only one unit for length: the meter. Centimeters aren't a different unit, they're "hundredths of a meter".

You can call your lengths of timber "frobs" if you want, even in public! You could have people order them that way and sell them that way. The only requirement most places have is that you also specify what that is in meters so that people who don't know what a frob is, know what they're buying.

It just makes sense that your frobs should be a useful number of meters so that they can be divided or handled easily and don't require 15 decimal places to express.

Edit: I have a question for you: would you support changing your currency away from 100 cents to the Dollar to something like the old Pound with 240 pennies to the Pound?

After all, if you're talking about measurements everyone uses and need to divide up, it's far more commonly required for cash in people's everyday lives than length or volume or anything else!

[jwecker]

You mean similar to how stock prices used to be demarcated or how foreign exchanges use 'pip' values? ;-) (http://www.cringely.com/2012/09/05/ticked-off-how-stock-mark...)

Seriously though good question. First though it made me realize that you never see prices in thirds of a dollar- as if everyone avoids it and have simply gotten used to avoiding it. I can't imagine a situation where ease of dividing by three for money actually adds any efficiency. Similarly, while I do see the value in dividing the day into 24 hours, I certainly wouldn't advocate a unit that's defined as one 60th of a second (even though it has even more prime factors than 12 ;)

I concede that the use-cases where having more prime factors and therefore easy non-decimal division are few and far between. I guess what surprised me when doing construction was that there was a very rational reason for a foot being 12 inches rather than 10- that it's not simply a relic of the fact that a human foot seems to be about 12 thumbs long- some arbitrary number accidentally ingrained in some cultures. And as illustrated by the fact that stocks were eventually decimalized and then made to trade at penny-granularity, computers and the fact that we don't do a lot of division in our heads or on paper anymore will probably eventually erase most remaining efficiencies.

[phaemon]

> I certainly wouldn't advocate a unit that's defined as one 60th of a second

Veering sharply offtopic, seconds are actually called seconds because they're "second order minutes". So, just as a minute is 1/60 of an hour, a second-order minute is 1/60 of 1/60 of an hour.

In the past, people have indeed used "thirds" (1/60 of a second) and in the 13th century, Roger Bacon went as far as using "fourths" (1/3600 of a second)!

[xxs]

Forex uses pips which are 1/10000 for EUR/USD, GBP/USD and the like or 1/1000 for USD/JPY. There are "sub-pips" that are 1/10 of a pip.

Pips are decimal, similar to millimeter that's 1/1000 of a meter. The point doesn't stand, imo.

[Dylan16807]

I actually would support changing the divisions of the dollar to a non-base-ten standard. Specifically I would make it dollars and quarters and dispense with anything smaller. We used to have a half-penny coin. We got rid of it when a penny was the same value as a quarter today.

[jarek]

http://en.wikipedia.org/wiki/1-2-5_series#1-2-5_series and start at 10c or 20c.

Actually, arguments advanced to support the American penny are interestingly similar to those advanced to support the American customary measures.