How is the density of a unit cell calculated?

The density of a unit cell is calculated using the formula:
$d = \frac{Z \times M}{N_{A} \times a^{3} \times 10^{-30}} \text{ g/cm}^{3}$
Where:
$Z = \text{Number of atoms per unit cell}$
$M = \text{Molar mass in g/mol}$
$N_{A} = \text{Avogadro's number } (6.022 \times 10^{23} \text{ mol}^{-1})$
$a = \text{Edge length of the unit cell in picometers (pm)}$
$d = \text{Density of the unit cell in g/cm}^{3}$