"This person needs to read more."
Translation:Этому человеку нужно больше читать.
why not "этот человек должен больше читать"? должен / нужно technically means the same?
Meanings of these words partially overlap, but they're not completely the same.
До́лжен (feminine должна́) usually has the meaning of obligation (я должна́ прийти́ = I must / have to / am to come) or prediction (он до́лжен прийти́ = he will probably come). Ну́жно usually has the meaning of neccessity (мне ну́жно прийти́ = I need to come, I have to come).
I was always taught that надо is used when you need to do a verb, нужно is for when you need a noun.
But according to this that's wrong, so I don't know if Duolingo is in error.
Надо is used with verbs. Нужно can be used with either but when used with nouns you must decline it (I.e нужен, нужна, нужны)
I've been told that besides how sentences are formed with each that they pretty much mean the same thing but надо is more colloquial.
I think that would mean something more along the lines of "This person needs to read a lot".