. . "\\(n = \\frac{N}{V}\\), where \\(N\\) is the number of particles and \\(V\\) is volume."^^ . "http://www.iso.org/iso/catalogue_detail?csnumber=31894"^^ . "n" . "http://dbpedia.org/resource/Number_density"^^ . . "In physics, astronomy, and chemistry, number density (symbol: n) is a kind of quantity used to describe the degree of concentration of countable objects (atoms, molecules, dust particles, galaxies, etc.) in the three-dimensional physical space." . . "http://en.wikipedia.org/wiki/Number_density"^^ . . "Number Density"@en . . . . .