Your example is right on this context. You could have say:

C’est bien ça?

I would have answered

C’est bien ça!

It means you were pretty sure to be right, but ask for confirmation.
Another example:

Avez-vous bien renvoyé le formulaire comme demandé?

We use that to insist on the fact you should know that statement, but ask just for confirmation.

Use of bien is not only for questions, it works the same way in statement. Both means that we are almost 100% sure of it:

J’ai bien renvoyé le formulaire comme demandé.