| quantity involved in counting objects or events individually identified
NOTE 1 – A number of entities is a quantity of dimension one.
NOTE 2 – The quantity ”number of entities" can be regarded as a base quantity in any system of quantities.
NOTE 3 – The values of numbers of entities are expressed by integer numbers, but statistical elaborations may be carried out.
NOTE 4 – Examples of numbers of entities:
• number of inhabitants of a given country at a given date;
• number of turns in a coil;
• number of molecules in a given sample;
• degeneracy of the energy levels of a quantum system.