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frereubu 2 hours ago

> The clathrate’s “cage” shapes are 12-sided dodecahedrons and 14-sided tetrakaidecahedrons made of silicon atoms...

Totally OT but if "dodeca" means 12, why isn't 14 just "tetradeca"? What's the "kai" for?

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normie3000 2 hours ago | parent | next [-]

kai means "and"

I guess like asking why 120 is said "one hundred and twenty" in some dialects.

Maybe that's how 14 and 12 are written in Greek.

	▲	frereubu 2 hours ago \| parent [-]
		Ah I see, thanks!

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gapan 2 hours ago | parent | prev [-]

As the sibling comment already said "kai" (pronounced ke like in keg) just means "and". So it literally means 4 and 10 sides in greek. But I have often seen it written as τετραδεκάεδρο (tetradecahedron) in greek as well, so without the kai part. I'm not sure why it is 4 and 10 instead of 14 though. It would be more natural in greek that way (δεκατετράεδρο - decatetrahedron). Maybe it is for putting the distinctive part (4) first, or maybe it sounded more "poetic" like that to someone and then it stuck.

	▲	shever73 3 minutes ago \| parent \| next [-]
		I think the three-and-ten, four-and-ten way of expressing numbers is primarily an ancient Greek thing. The modern numbers are expressed differently (δεκατέσσερα / dekatessara for fourteen, for example). In a lot of older European languages 11 and 12 behaved irregularly. You could argue that they do in English too (we don't have oneteen and twoteen). I haven't read of any particular reason for this, but I'd posit that numbers up to twelve were more commonly used in everyday life, so shorter, irregular forms were easier to use and remember. Much like many of the irregular verb forms in spoken language happened because they were so commonly used. The ancient Greek system also gave us triskaidekaphobia - the fear of the number 13.
	▲	corkybeta 16 minutes ago \| parent \| prev \| next [-]
		Four and twenty blackbirds, baked in a pie. https://en.wikipedia.org/wiki/Sing_a_Song_of_Sixpence
	▲	fhars 34 minutes ago \| parent \| prev [-]
		Nobody would be so weird as to put the "four" first when pronouncing "14". :-)