Where does “siæx” come from?

siæx (Old Swedish) comes from Old Norse sex, from Proto-Germanic sehs, from Proto-Indo-European swéḱs — six.

Ancestry of “siæx”, step by step

StepLanguageWordMeaning
1Old Norsesexsix
2Proto-Germanicsehssix
3Proto-Indo-Europeanswéḱssix
Every word from Proto-Indo-European swéḱs →Every word from Proto-Germanic sehs →Every word from Old Norse sex →