Without specific information about the points P and Q, or any context regarding what "n" refers to, I'm unable to provide a precise answer.
If P and Q are points in a two-dimensional space with coordinates (x1,y1) and (x2,y2), respectively, the distance between them can be calculated using the formula: √[(x2-x1)² + (y2-y1)²].
"N" could refer to many things depending on the context - it could represent a variable in an equation that needs to be solved, it could refer to a number in a sequence, etc. Without specific details about where this question is derived from (e.g., a word problem, an equation, etc.), I cannot determine what n signifies or how to calculate its value.