Given scientific fact as input, generate the question from this fact such that it can be answered from the input.

To determine the atomic weight of an element, you should add up protons and neutrons.
How do you determine the atomic weight of an element?

Low energy causes waves to bring sand up onto the beach during summers.
What causes waves to bring sand up onto the beach during summers?

Pluto has three moons.

How many moons does pluto have?