The Metric Caboose

By The Metric Maven

Mini-Bulldog Edition

As a boy, I lived less than a block from a set of railroad tracks. The report of train whistles, and the low pitched sound of each train as it passed by during the night assured me commerce was underway, and all was fine. During the day, myself and others would often watch as a train passed to see what the oldest car was. The oldest was 1909 as I recall, and those cars looked very fragile. Of course the caboose was a punctuating symbol that defined the end of the train. I don’t ever recall a caboose at the front of the train. A caboose at the front of a train, before the engines, would be seen as something out of order, that is not being used as designed. Could one hook a caboose to the front of a train and have it operate? Sure—does it make sense–perhaps—but not as expected usage.

When I first became interested in electronics, resistors were the first component I encountered. Their resistance is measured in ohms. One might have 50 ohm resistor, or 68 ohm resistor, but when the value progresses into the thousands, the metric prefix Kilo is used. A 10 000 ohm resistor is a 10 Kiloohm resistor which is generally written as 10 KΩ, when the resistance becomes large enough we use Megaohms or MΩ. As people like to speak in shorthand, and everyone knows, that on an electrical schematic, resistors are in ohms, electrical engineers generally say “that’s a 4 K resistor,” implying that the value is 4 KΩ. When people say they are going to participate in a 5K run, it’s understood that it is a 5 Km distance.

The metric prefix Kilo- is supposed to modify the unit value that follows it, but in common usage, people often appear to use it as shorthand for a set of zeros. When the prefix symbol is moved next to a numeral, 5K becomes 5000; the prefix modifier becomes a suffix modifier. When it is thought of in this way, it can be used as a sort of stealth prefix for Ye Olde English, or whatever comes along.

For instance here is an example from the web where the metric modifier is separated from Olde English as if this is a good idea:

So it reads “Spruce beetles pick up where their pine cousins left off, eating through 136 000 acres in past year” rather than “Spruce beetles pick up where their pine cousins left off, eating through 136 Kiloacres in past year.” The prefix modifier becomes a suffix modifier and metric is “compatible” with anything. Just by removing a space we modify the leading number rather than the trailing unit. By invoking this idea, we create 5K dollars, or 75K crickets, or 210K albatrosses. This space removal causes a literary switcharoo that turns a prefix into a suffix. This appears to be a practice that has happened somewhat recently and has become an accepted part of the language. If there is no space between it and a leading number, the single metric “prefix”  becomes a suffix number, and if there is a space then a metric unit must follow the prefix.

Is this usage a good idea? I’m not sure. Perhaps this is a usage that could make sense. Without a space 326K, or 326M, or 326G could be thought of as numbers. The value 326G certainly is more compact than 326 000 000 000. This distinction would have to be identified, formalized, and taught in schools, so that students would know how to use it properly. If one writes 25K they mean a number, if they write 25 K then one should expect a unit symbol to follow such as 25 Km, and 25 K would not be considered a finished statement. I can see how this usage could be useful, but currently it strikes me as the engine switched for the caboose.

Related essay:

The Elements of Bile

If you liked this essay and wish to support the work of The Metric Maven, please visit his Patreon Page and contribute. Also purchase his books about the metric system:The first book is titled: Our Crumbling Invisible Infrastructure. It is a succinct set of essays  that explain why the absence of the metric system in the US is detrimental to our personal heath and our economy. These essays are separately available for free on my website,  but the book has them all in one place in print. The book may be purchased from Amazon here.

The second book is titled The Dimensions of the Cosmos. It takes the metric prefixes from yotta to Yocto and uses each metric prefix to describe a metric world. The book has a considerable number of color images to compliment the prose. It has been receiving good reviews. I think would be a great reference for US science teachers. It has a considerable number of scientific factoids and anecdotes that I believe would be of considerable educational use. It is available from Amazon here.

The third book is called Death By A Thousand Cuts, A Secret History of the Metric System in The United States. This monograph explains how we have been unable to legally deal with weights and measures in the United States from George Washington, to our current day. This book is also available on Amazon here.

7 thoughts on “The Metric Caboose

      • Did the BIPM & CGPM authorize the change? I must have missed the announcement? Can you provide documentary proof of the change?

  1. Writing something like $7.5k for $7500 has been in existence since at least as far back as the early 1970s — just check an employment ad in the NYTimes back then.

    Wrt K instead of k, I have come to agree with you when such is an SI-related prefix but think something like the $7.5k is all right.

    What is really sickening is calling a 10-km race a 10K race (or “10k” race). But this sort of jibes with those in this country who will do anything to avoid the base-unit word here, the meter.

    Furthermore, there are those who try to shun the power-of-ten prefixes too. (Of course they are okay with the corresponding power-of-two prefixes.) The most extreme shunning I have seen (or, more accurately, not seen) concerned the phrase Y2K (or Y2k) back in that year. Although the NYTimes used the phrase often, not once do I recall the paper ever telling the reader that the K (or k) stands for kilo or 1000!

  2. Uh, little problem with this one: A capital K is the SI symbol for the Kelvin, so I end up reading “25 K” as “Twenty-five Kelvin”, not as the incomplete statement you were suggesting.

    As something a little more positive, when talking about things like the budget for a government program, I occasionally use “gigabucks” to describe the amount of money it costs.

    • There is really no problem here as 25 K could only mean 25 Kelvin and 25 Km, 25 Kg, et al could only mean 25 kilometers, 25 kilograms, et al.
      If we consider your argument further, then what about m for meter and m for milli- ?
      In a nutshell, we would still have unique symbols for units and likewise for prefixes.

      On another thing that should be of interest to the Maven, his disciples, and others, is that, due out on June 16th, there will be a film with the title “47 Meters Down” (and not, thank goodness, something like “155 Feet Down”).

      Here’s some info on this film:

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