köken: Inherited from Proto-Slavic *na desęte. Compare Old Church Slavonic на десѧте (na desęte), Polish -naście. By surface analysis, на (na) + десять (desjatʹ), literally “on ten”.
три (tri, “three”) + -надцать (-nadcatʹ) → трина́дцать (trinádcatʹ, “thirteen”)
köken: Etymology tree Proto-Slavic *na desęte Polish -naście Inherited from Proto-Slavic *na desęte. By surface analysis, univerbation of na + dziesięć, literally “on ten”.
köken: Inherited from Proto-Slavic *na desęte. Compare Old Church Slavonic на десѧте (na desęte), Polish -naście, Russian -надцать (-nadcatʹ). By surface analysis, на (na) + десять (desjatʹ), literally “on ten”.
три (try, “three”) + -надцять (-nadcjatʹ) → трина́дцять (trynádcjatʹ, “thirteen”)
-teen (suffix which in Finnish forms the numbers 11 to 19)
köken: From the partitive singular toista of toinen (“second”), by ellipsis of the phrase toista kymmentä (literally “of the second decade”), referring to the second ten of numbers (11–19). yksitoista, for example, originally was yksi toista kymmentä (literally “one of/into the second decade”), as the first "decade" (first ten numbers) were already counted. This system used to be used more widely, but…
köken: Univerbation of spre + zece, literally “to ten”. The formation is otherwise unknown to the Romance languages, and was influenced by neighbouring languages, such as Albanian -mbëdhjetë and Old Church Slavonic на десѧте (na desęte).
un (“one”) + -sprezece → unsprezece (“eleven”)
cinci (“five”) + -sprezece → cincisprezece (“fifteen”)
köken: From li̇̀kti (“to stay, be left”), denoting how many are left over after counting to 10. For a semantic parallel (albeit from a different Indo-European root), compare Proto-Germanic *-lif.