One of the first things most people do when learning a new language is to learn the numbers from 1 to 10, and shortly after that, from 11 to 20. And it’s generally quite easy to remember them in the case of European languages, as they’re somewhat similar to their English counterparts. Look at French, for example:
Un, deux, trois, quatre, cinq, six, sept, huit, neuf, dix.
Not necessarily all obvious individually, but seen all together, they’re clearly the first ten numbers. The same goes, I think, for 11 to 19:
Onze, douze, treize, quatorze, quinze, seize, dix-sept, dix-huit, dix-neuf.
Clearly a combination of ten and the relevant number, and the same applies to English (eighteen = eight + ten, for example). Except, that’s not quite true in every case, is it? What about 11 and 12? They don’t fit the pattern at all. Twelve has a clear link to two, but not ten, and eleven seems to be unrelated entirely to either one or ten. What’s going on there then?
The most-accepted theory is that while eleven and twelve might not follow the same pattern as the seven numbers that follow, they’re still constructed in a similar way.
Most linguists agree that eleven is derived from the Old English enleofan, which means one left over (i.e. ten and one left over). Which seems like a slightly convoluted way to go about it, but it does make sense, after a fashion. Twelve probably has a similar origin, coming from twelf, meaning two left over.
So that’s that oddness explained then. But why aren’t 13 to 19 constructed in a similar way? It might be that 12 was considered special, being the number of months, lunar cycles, and signs of the Zodiac, among other things. And mathematically it’s a useful number, being divisible by 1, 2, 3, 4, 6, and 12. Everything after that, well, that’s all pretty ordinary, so just use the same pattern for them and let’s call it a day.
And The Twoteen Days of Christmas just doesn’t sound right, does it?
English-Language Thoughts 
Love these little linguistic explorations! Very interesting.
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Eleven and twelve are considered sacred numbers. Eleven is the doorway (two pillars) into other realms. Twelve is traditionally thought of as a perfect number, possibly because when reduced it is three. Three is the magical number: 3 wishes, third time’s a charm, etc. 🙂 So I suppose there is a method to it!
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I never knew that about eleven, that’s cool!
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Oh yes, eleven is a big deal 🙂
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I loved the french language of numbers
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I’m glad that 11 and 12 are named eleven and twelve since if not, then we would not have this curious anagram:
ELEVEN + TWO = TWELVE + ONE
While you can still do it with oneteen and twoteen, it’s not as elegant.
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That’s definitely a fun fact :).
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I wonder if other languages have the equivalent of the word “teenager” or is that peculiar to the English language?
Google translates “teenager” into French as “adolescent”, but I don’t think that’s an exact equivalent (a 12 year old might be considered an adolescent but not a teenager, while 19 year old would likely be considered a teenager but not an adolescent).
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I don’t think so, I think most equivalents would be like “adolescent” and based on physiology rather than anything else. It’s interesting that the word only really started to be used with any frequency well into the 20th century. Before then you were really either a child or an adult.
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Or at some point in the linguistic journey a Base system collided with a Base 12 system. There is anecdotal evidence that counting systems have a residual Base 20 system in some parts of Northern england
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And having thought a bit more don’t we have residualduodecimal? I would say half a dozen, not more logical about half a 10
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Travelling to work today is taking forever. Don’t let the official business timetable put the sheep over your head!
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