Number of atoms in a unit cell

The unit cell of a simple cubic system has atoms at the eight corners. Hence, number of atoms in an unit cell is

The number of atoms in hcp unit cell is………… .

A cubic unit cell has one atom on each corner and one atom on each body diagonal. The number of atoms in the unit cell is

Sodium crystallises in a cubic lattice and the edge length of the unit cell is 430 pm. Calculate the number of atoms in the unit cell. (Atomic mass Na = 23 amu, Density of Na = 0.9623 g cm^(-3) )