Language Of Confusion: Weird Numbers

I’ve done all the numbers one to ten, and some of the major ones, but how about all those weird ones?
 
Like eleven. Why is it not one-teen? It showed up in the thirteenth century spelled elleovene, from the Old English endleofan which I’m glad we don’t have to spell any time we write eleven. It’s from the Proto Germanic ainlif-, where ain- means one and the rest is from the Proto Indo European leikw-, to leave. Eleven is, somehow, one plus to leave. Apparently it’s because Anglo-Saxon would use leave (spelled laf) in reference to leavings. Eleven is basically saying “one left over”, i.e. from ten.
 
Twelve is basically the same. It’s from the Old English twelf, from the Proto Germanic twa-lif-, where twa- is from the Proto Indo European dwo-, two. Twelve is two left over! Then there’s dozen, which showed up in the fourteenth century as doseine. It’s from the Old French dozaine and classical Latin duodecim, twelve—duo, two, plus decim, ten. So those two words were shoved together and the middle morphed into the Z sound.
 
Plus there’s also ordinal numbers, which from four on are just the number plus -th, but the first three are kept weird. First is especially bizarre, since it seems to have nothing to do with one. It showed up sometime before the sixteenth century, coming from the Old English fyrst. It’s actually the superlative of the word fore, as in first is to fore what worst is to worse, and it can be traced to the Proto Germanic furista- and Proto Indo European pre-isto-, which is actually related to per-, the suffix meaning forward. So first is first because it’s first.
 
Then there’s second, which, again, nothing in common with two. It showed up in the fourteenth century from the Old French second and classical Latin secundus, which means, well, second, the thing that follows. It can be traced back to the Proto Indo European sekw-ondo-, from sekw-, to follow. Second is second because it follows first.
 
Third at least has letters in common. It comes from a mix of the Old English þridda, third, and the Proto Germanic thridja-, they just switched the R and the I. It’s from the Proto Indo European tri-tyo-, which is from trei- the origin of three. It seems like there’s no real reason it’s weird other than it just stuck around and people reversed the letters.
 
Sources
Online Etymology Dictionary
Google Translate
Omniglot
University of Texas at Austin Linguistic Research Center
University of Texas at San Antonio’s page on Proto Indo European language
Tony Jebson’s page on the Origins of Old English
Old English-English Dictionary