“Сорок” used to mean a bundle of furs, a trade unit, and in general to mean “many".

There is also the word “тысяченожка” (thousand-footer, millipede). I guess, neither of them is typical for the Russian climate, so almost no-one has ever seen them for real, and nobody knows the difference.

That’s very helpful. Centipedes are really dangerous. Having all above mentioned background knowledges will be very important for everybody.

I wouldn’t be so sure, that those numbers mean nothing. They match, at least in order of magnitude. These creepers are not called micropedes or nanopedes, are they? (I know, most of people didn’t probably use such a big numbers, but still.)
Btw centi is 1/10^2 not 10^2 and mili is 1/10^3 not 10^3. So literally centipede should have one hundredth of legs :-D

I think that Moscow might have had about 1600 churches when someone thought up this idiom, why not.

Something I found googling:

Нужно отметить, что в старом русском счете сороковой не только четвертый десяток, а и самостоятельная единица счета. Например считали соболей сороками. Говорилось ‘в Москве 40 сороков церквей’ но церкви делили на сороки, в каждой было меньше 40 церквей.

Don responds: Your thought about orders of magnitude is, I think, quite to the point. An ancient Roman looks at a centipede and thinks, “Wow, that’s a lot of legs. There must be a hundred of them.” He looks at a millipede and thinks, “Wow, it has even more legs than a centipede. There must be a thousand of them.” My point here is that the numbers are not being used with scientific precision, and they are not meant to be understood as having scientific precision. Similarly, labeling an area with a great many churches as a сорок fits in with the concept of numerical hyperbole, particularly when those areas in fact did not have forty churches each. BTW, your comment about the relationship of centi- to the meaning of one one-hundredth made me smile. One of these days I’ll pen a rant related to that topic.

I wonder where these numbers came from. 40, 100, 1000, many…
In czech language ’stonozka’(hundred-footer) means centipede and ‘mnohonozka’(many-footer) means milipede. But most people use ’stonozka’ for both of them anyway.

I checked the wikipedia and other sources and the numbers make sence to me now. Wiki says that milipedes have between 36 and 400 legs. One species has even 750. Centipedes may have as few as 15 pairs, others have as many as 173 pairs, but most sorts have about 35 pairs.

Anyway, they are all very nasty!

Don responds: I think the approximate number of legs has little to do with the names. There is a figure of speech that we may call “numerical hyperbole.” Essentially the number is used to mean “a whole lot of.” For instance, when the secretary in a small office says, “We must have had a million phone calls today,” she doesn’t mean precisely a million calls. She means “a whole lot of calls.” And she is not lying. She is using a figure of speech that is correctly understood by everybody who hears her. Thus traditionally it was said «В Москве 40 сороков церквей» “Moscow has forty forties of churches.” There weren’t literally 1,600 churches. It means “a great many churches.” So a Roman could look at a centipede and think, “Wow, it must have a hundred legs.” Thus the Latin word is born.

Don’t “centipede” and “millipede” mean in latin “hundred-footer” and “thousand-footer"?

Don responds: Precisely! The Russian words, though, are much more transparent to a Russian than the English words are to an English speaker. Every Russian knows that сорок and ножка mean forty and leg, respectively. I think most English speakers do not know that the -ped- root meant foot in Latin, and unless they work in the sciences, many Americans will forget that centi- and milli- mean hundred and thousand, respectively.