As a non physicist, non scientist, I have a question, which may be really stupid

As a non physicist, non scientist, I have a question, which may be really stupid

As a non physicist, non scientist, I have a question, which may be really stupid. If quantum mechanics expounds that at an atomic level matter can be in 2 places, at one point in time, does this matter have mass in these 2 different places? If this matter can have a mass in more than one place, at one point in time, how can we attempt to calculate the mass of matter present in the universe as surely it would depend on what proportion of matter was in what number of places at any point in time? Does that mean its unit of measurement would need to include number of atoms, the proportions of this matter in what numbers of places, at a fixed point in time? Is there some basic reading that might help me understand this a bit more? Thank you.

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