"Twenty, twenty-one, twenty-two, twenty-three, twenty-four, twenty-five"
Translation:Twintig, eenentwintig, tweeëntwintig, drieëntwintig, vierentwintig, vijfentwintig
Good question. One/één gets the accents to differentiate between a/an/een and one/één. Since there is no such issue with eenentwintig the accents are not needed.
I wrote without the two dots on the e's and it was accepted, should it be or is it a mistake?
It's not correct to leave out the diaeresis (trema in Dutch). But in other languages I know this kind of mistake was accepted with a "you made a mistake" warning, I think this should be the case here as well.
I think they accepted it because not many people have the trema on their keyboards, and it's tedious to always click it.