Numbers... numbers are funny things, and human languages have all sorts of quirks in regards to them. For instance, the Ya̧nomamö tribe in South America has only three number words: one, two, and “more than two.” In Arabic grammar a feminine noun agrees with a masculine number and vice-versa, at least for the numbers three to ten. English has a word for a dozen dozens. Lusatian and Slovene have not only singular and plural noun endings, but also dual. And among the quirks of the Slavic languages is this little gem: Russian has a word that means “one and a half,” and that word is полтора/полторы. It declines like this:

Like the numbers два/две, три, and четыре, this number is followed by the genitive singular of the noun that it quantifies. Sample sentences:

Upon reflection one might wonder how the heck a language comes up with a single word for “one and a half.” After all, a caveman is not going to go out looking for one and a half yaks, and a prehistoric Slav never looked for one and a half wives. So why a number for “one and a half”? The reason is simple: it originally came from two words. The Old Russian word for half was полъ, where the final letter was a spoken vowel. The word for second was вторъ, which in the genitive case was втора. When speaking of quantities, ancient Russians talked about “half of the second” «полъ втора» item, and they assumed the listener knew that if they were talking about half of the second, they of course also meant all of the first item as well. Or if talking about a feminine thing they used вторы, which is the feminine genitive form of second. Eventually the vowels ъ and ь started vanishing from the language, which meant in terms of pronunciation they were left with полвтора and полвторы. Languages have the tendency to simplify consonant clusters, and the в eventually vanished (which is the same reason we pronounce здравствуй as [zdrastvuy] not [zdravstvuy].

¹ ГАЗ = Горьковский автомобильный завод = the Gorky Automobile Factory.