"Tuesday is the second day of the week."
Translation:Hogh jaj cha' 'oH povjaj'e'.
When a number without a suffix follows a noun, it's used for counting. Hogh jaj cha' weekday number two. There's not much difference between saying that and saying Hogh jaj cha'DIch second day of the week. The Duolingo example is clearly thinking of these as interchangeable. Whether that's fair or not, I don't know.