"Eu moro em uma cidade."

Translation: I live in a city.

[MarcoPerez1]

I wonder why the contraction "eu moro numa cidade" doesn't work

[Paulenrique]

that should work too!

[MarcoPerez1]

agreed!

[Chadirino]

In Potugal, "em uma" isn't even used. At least in the case of "um" being an article and not a number. It should be accepted, MarcoPerez1.