* NaCl represents one formula unit: This means it contains one sodium atom (Na) and one chlorine atom (Cl).

* Multiply by 12: Since we have 12 formula units of NaCl, we multiply the number of atoms in one formula unit by 12.

Calculation:

* 1 formula unit of NaCl = 1 Na + 1 Cl = 2 atoms

* 12 formula units of NaCl = 12 * 2 atoms = 24 atoms

Therefore, there are 24 atoms in 12NaCl.