Here's how to calculate the number of atoms in the molecule C13H18O2:

* Count the atoms of each element:

* Carbon (C): 13 atoms

* Hydrogen (H): 18 atoms

* Oxygen (O): 2 atoms

* Add the number of atoms together: 13 + 18 + 2 = 33 atoms

Therefore, there are 33 atoms in the molecule C13H18O2.