Learn Dutch: Daarom moet de formule op het scherm zichtbaar zijn. - Therefore, the formula must be visible on the screen.

Not quite! While moeten often means a strict obligation, here it is used for logical deduction. The speaker is drawing a conclusion based on prior information (indicated by Daarom, meaning 'Therefore'). They are saying it only makes logical sense, or it is a necessary logical consequence, for the formula to be visible on the screen.

Why is the word order moet de formule instead of de formule moet?

Because the sentence starts with Daarom. In Dutch, the conjugated verb (moet) insists on being in the second position of a main clause. When you put a word that isn't the subject at the very beginning, the subject (de formule) has to swap places with the verb and go immediately after it. This is called inversion.

Why is the verb zijn placed all the way at the end?

When you use a modal verb like moeten in the second position, the other verb in the clause gets pushed to the very end in its infinitive (full dictionary) form. So zijn (to be) waits at the end of the sentence.

Could I say zichtbaar te zijn instead of just zichtbaar zijn at the end?