If a pin is 0.001 m wide, how many RBCs could you line up across a pin

The average human red blood cell is roughly 6 to 8 micrometers wide. The width of a pin is this problem is defined as 1000 micrometers. Assuming we use the smallest size of a blood cell, then we divide 1000 by 6, and we find that roughly 166.66 (or 166 if you are rounding down) red blood cells will fit.