So Mandarin has a pretty regular syllable construction. Usually, it's consonant-vowel. It cheats a little sometimes in a few ways, like ending on an n or an r or beginning with a w or a y and pronouncing the glide in such a way that it sounds somewhat like a vowel sound. These things make pretty good sense. And one of the first things I learned in my classes on Mandarin was that Chinese syllable construction works in this particular strict way.
And then along comes the numeral 2, which is written as the character 二. In the romanized form, it's written as "èr," which sounds like the English word "are" with a descending tone. That's an unambiguous vowel-consonant syllable, and it uses none of the standard tricks. It seems out of place. Is it a vestige of an earlier form of Mandarin that allowed for more lax syllable construction? Are there more words that break the rules? It's a natural language, so that would make sense. Has someone looked into this?
This might be more of a linguistics question than anything, but I'm curious about it and don't know how to Google it properly. Some answers would be appreciated.