Email Print Number Density Written by Jerry Ratzlaff on 22 January 2016. Posted in Classical Mechanics Number density, abbreviated as n, is the number of items per unit volume. Number Density formula \(\large{ n = \frac {N}{V} }\) Where: \(\large{ n }\) = number density \(\large{ N }\) = total number of items \(\large{ V }\) = volume Tags: Equations for Volume Equations for Density