$\text{ In face centred cubic lattice, a unit cell is shared equally by how many unit cells }$

$\text{ An isolated }fcc\text{ cell is shown here. Each face of the cell is common to two adjacent cells. Therefore, each face centre atom contributes only}$$\mathrm{half} \mathrm{of} \mathrm{its}$
$\mathrm{volume} \mathrm{and} \text{ mass to one cell. Arranging six cells each sharing the remaining half of the face centred atoms,constitutes fcc cubic lattice. e.g., }\mathrm{Cu}\text{ and }\mathrm{Al}\text{. }$