The numbers of tetrahedral and octahedral holes in a ccp array of 100 atoms are respectively

A unit cell is obtained by closed packing layers of atoms in ABAB …… pattern. The total number of tetrahedral and octahedral voids in the unit cell are respectively

The number of terrahedral and octahedral holes in a hexagonal primitive unit cell are respectively:

Total number of tetrahedral and octahedral voids in hcp arrangment are 12/18 .

In octahedral holes (voids):