The atomic number of zinc is 30, which means that a neutral atom of zinc has 30 protons. Zinc-66 has a mass number of 66, which means that the sum of the number of protons and the number of neutrons is 66. Therefore, the number of neutrons in zinc-66 is 66 - 30 = 36.

Since the atom is neutral, the number of electrons is equal to the number of protons, which is 30.