how do u use usar in this sentence..(Que numero usar usted?

Question

Qué número usar usted?

Answer 1

usa= meaning wear

número= size

What size do you wear?

Answer 2

Context is important and by the way this is a double post. You already have this questioned listed.

Answer 3

Que numero usa usted because you are speaking directly to another person. Conjugations go like this:

yo nosotros tu vosotros (spain) el/ella ellos

this would be (in order from top)

uso usamos usas usais(?) usa usan

But since saying usted is formal, you conjugate the tu version like an el/ella version, hence it is usa usted instead of usas usted.