# octahedral interstitial sites located entirely within a full hexagonal HCP unit cell at a height of $c/4$ up from the bottom of the unit cell

I have been trying to visualize and find the number of them for a while, through the image attached.

I can't tell whether the c/4 part includes the octahedral site or not...how should I go about approaching this problem?

• Those white dots are the octahedral/tetrahedral sites (respectively). Those white dots on the left are at c/4 and 3c/4... – Jon Custer Mar 15 at 16:40
• so would you say there are 3 full sites in the c/4 region or 0? – A. Radek Martinez Mar 15 at 16:52