Where does “femtan” come from?

femtan (Norwegian Nynorsk) comes from Old Norse fimmtán, from Proto-Germanic fimftehun, from Proto-Germanic tehun, from Proto-Indo-European déḱm̥t — ten.

Ancestry of “femtan”, step by step

StepLanguageWordMeaning
1Old Norsefimmtánfifteen
2Proto-Germanicfimftehunfifteen
3Proto-Germanictehunten
4Proto-Indo-Europeandéḱm̥tten
Every word from Proto-Indo-European déḱm̥t →Every word from Proto-Germanic tehun →Every word from Proto-Germanic fimftehun →