Here's how to figure out the number of atoms in Fe₂O₃ (iron(III) oxide):

* Subscripts represent the number of atoms: The subscript '2' after Fe means there are 2 iron (Fe) atoms.

* The subscript applies to the element it follows: The subscript '3' after O means there are 3 oxygen (O) atoms.

Therefore, there are a total of 5 atoms in a molecule of Fe₂O₃.