text: The number of entities (symbol N) in a one-mole sample equals the Avogadro number (symbol N), a dimensionless quantity.
  Historically, N approximates the number of nucleons (protons or neutrons) in one gram of ordinary matter.
  The Avogadro constant (symbol ) has numerical multiplier given by the Avogadro number with the unit reciprocal mole (mol).
  The ratio  is a measure of the amount of substance (with the unit mole).