why do i need the den here?please help anyone
When you use a noun with an adjective, you also typically need a definite article before it. So you show definiteness in 3 places. The separate word den (the), the ending -a in röd, and the definite article -n in mattan.
So if we were talking about a red ett-word, woukd it be "det röda ett-definitive"?
Tack, Lundgren8: exactly why I came to this discussion. That is definitely a real definite love of definiteness!