When identical particles pack in a simple cubic lattice, there is/are particle(s) per unit cell?

            When identical particles pack in a simple cubic lattice, there is ONE particle per unit cell.

Explanation:
                   As we know that simple cube has eight corners and each particle at every corner is shared by eight cubic crystals. So it means that only eighth part of a particle is present at one corner of each cube. Therefore, each corner contain 1/8 particle, then all corners will contain 1/8 × 8 = 1 particle.