Talk:Metre

message: I removed the mnemonic ("1 metre is nearly equivalent to 3feet inches."), and  put it back. Nothing to make a big fuss about, but fwiw, here is why I removed it:
* It is not encyclopedic information, rather it is a "how-to" hint for learners. It is possible that in fact this is/was a widely taught guideline in some circumstances, in which case there should be a cited reference to this as a social phenomenon.
* It is not very good: actually you have to remember not just "three 3s", but "3 3 3 8", otherwise you might misremember it as 3' 3 3/4" or 3' 3 3/16".
* It is not actually much use: back-of-the-envelope calculations these days are done with calculators, but you would need a calculator supporting mixed-base arithmetic and binary fractions (as in the problems I did at primary school: divide 3' 3 3/4" by 7).
* You only need to remember "one inch = 2.54 cm" (three digits, again), and you can calculate anything precisely correctly using a normal calculator.
Imaginatorium (talk) 14:05, 4 September 2023 (UTC)
replies: text: The points Imaginatorium makes about calculators being ubiquitous are valid. But if someone in the US (and perhaps the Canadian building trades?) were faced with measuring out a length stated as a whole number of meters and only had a customary tape measure, the mnemonic would be useful. I'm not sure if that's common enough to be worth mentioning. Jc3s5h (talk) 14:12, 4 September 2023 (UTC)
replies: text: They also need to still have good mental arithmetic (despite calculators) to convert 3 or 4 metres to feet and inches with this mnemonic, and we already have a narrow audience anyway (US building trade, tape in customary units only being used to measure a round number of metres). NebY (talk) 15:33, 4 September 2023 (UTC)

text: In addition to Imaginatorium's points, that mnemonic was added in 2010 with the edit summary "created a simple mnemonic; 1 meter is 3 feet, 3 and 3/8 inches" and as a reference Original work; no known references ~ ~~~~.. That was changed to Well-known conversion, publicised at time of metrication. with the edit summary "well-known", presumably referring to Metrication in the United Kingdom in the 1970s (going by the editor's userpage, anyway). That ref was tagged  later in 2010 and removed in 2019. In short, the statement has never had a source for the mnemonic's existence, let alone the statements that it's simple and assists; all we have is an editor's claim that it was publicised about fifty years ago and is, or was, well-known somewhere. NebY (talk) 16:05, 4 September 2023 (UTC)
replies: text: I restored the paragraph because I think approximations are in principle knowledge worth including in an encyclopedia. The classic example is the various approximations of pi (22/7 etc.), which have considerable historical as well as practical significance. Generally I am also sympathetic to including useful well-known mnemonics in an article. Yes they are "how to", but they are also useful to readers, and often even a bit fun! But I agree now that the case for inclusion of this particular mnemonic is questionable. We don't need a reference to support its truth ("sky is blue"), but it would indeed be desirable to be able to show that it is or was in use rather than made up afresh by an editor. On the question of whether this mnemonic is useful, yes I think it is even in these days of mobile phones. We all know that a metre is a bit more than a yard, but this does indicate how much more in a handy, memorable way; it's really not as convenient to have to multiply 2.54 by 36 to work that out even if a mobile phone is within reach. So, if someone can find a reference to its use (which I couldn't), I would vote to keep it. JMCHutchinson (talk) 17:15, 4 September 2023 (UTC)
replies: text: Much as pi's historic and easily remembered approximation 22/7, plus calculators, left little demand for mnemonics for pi, I suspect that the approximation 3' 3", the precise 25.4 and tape measures in feet and metres left little room for this mnemonic. Many are created, few catch on. NebY (talk) 10:26, 5 September 2023 (UTC)
thread_title:  Mnemonic ("three threes")