Regarding denmark. Found on the red web
We say: to og halvfems which literally translates to two and ninety. Halvfems is just the word for ninety. The root of the word originates from a base 20 way of counting where the root of the English word ninety (9x10) originates from a base 10 way of counting. Its not like we do any math that way anymore, it's literally just a word that through time has been shortened a bit. The full word would be halvfemsindstyvende like the full word for ninety would be nine tens