David W. Oxtoby Quote

Laboratory or industrial chemical reactions are carried out with quantities that range from milligrams to tons, so we must be able to relate the relative atomic mass scale to the macroscopic scales used in practice. The link between the two scales is provided by Avogadro's number (NA).

Principles of Modern Chemistry (7th ed., 2012) - Ch. 2 : Chemical Formulas, Equations, and Reaction Yields