This might be the wrong sub for this. Feel free to delete me and point me in the right direction if it is.
My question specifically relates to the names "eleven" and "twelve". Starting at thirteen, you have the suffix -teen. Then twenty. The suffix -ty. Etc. everything before 10 is just a singular number. Everything after 13 follows a pattern of suffixes. So then why are 11 and 12 different? Why don't we have eleventeen or oneteen or something along those lines?
Eleven and twelve both derive from formations that meant 'one left' and 'two left' (with an implied "after ten"). The structure was preserved for these two numerals in West Germanic, and a similar structure is attested in Lithuanian, although it's used from 11-19 (e.g. vienuolika '11', devyniolika '19').
As for why 11 and 12 specifically are unique, the answer probably lies in word frequency. Frequency effects are well-documented in linguistics: more frequent words are learned faster by children, recognized faster by adults, see more phonological reduction in fast speech (i.e., they are said less clearly), and importantly for us here, they are "more conservative in the face of grammatical change or analogical change based on the analysis of other forms" (Bybee 2004). The underlying idea here (which is not original to Bybee, but which her 2004 book summarizes usefully) is that
Experience affects representation. The use of forms and patterns both in production [speaking, writing] and perception [hearing, reading] affects their representation in memory. High-frequency words and phrases have stronger representations in the sense that they are more easily accessed and less likely to undergo analogical change. Low-frequency words are more difficult to access and may even become so weak as to be forgotten.
We see this play out in other places: the verb do has a unique past tense form; likewise children is practically unique; the verb be is the only English verb with a distinct first-person singular present (am), or with number agreement in the past tense (was vs were). However, these forms are all common enough to resist having their paradigms regularized by analogy (at least in Standard English).
See these two threads from two years ago. Unfortunately, some of the posters' accounts have been deleted.
Follow up... Why is 10 through 19 different than any other part of number naming? If we followed the other number patterns less than 100, shouldn't it be:
Edit: It's probably rhetorical... because English is weird, but I always wondered if there was a significance to that. Is it because we only have 20 digits to count on?