What is the coordination number in a hexagonal close-packed $(h.c.p.)$ structure?

In a face centred cubic lattice,atom $A$ occupies the corner positions and atom $B$ occupies the face centre positions. If one atom of $B$ is missing from one of the face centred points,the formula of the compound is:

In a cubic structure of a compound made from $X$ and $Y$,where $X$ atoms are at the corners of the cube and $Y$ atoms are at the face centers of the cube,the molecular formula of the compound is:

$A$ solid has a structure in which $W$ atoms are located at the corners of a cubic lattice,$O$ atoms are at the center of the edges,and $Na$ atoms are at the center of the cube. The formula for the compound is:

An element has a $bcc$ structure with $12.08 \times 10^{23}$ unit cells. What is the total number of atoms in these unit cells?

The coordination number of cation and anion in fluorite $CaF_2$ and anti-fluorite $Na_2O$ are respectively