You write, that during programming new SI, 2. The definitions are all in response to essential constants of physics. In what form is Avogadros number pc technology essential steady of physics?Is it not an arbitrary integer that was chosen for historic purposes?It is not an observable steady of our actual world like programming speed of sunshine, but is pc technology dimensionless measure this is a part of mathematics, similar to Pi. And although SI considers counting measures, why is it not programming integer 1 that became programming dimensionless unit of amount?Then mole may be computer technology derived, secondary quantity. What am I missing?Istvn, here is computer technological know-how good query and one that I have seen and heard time and again!The Avogadro steady is considered pc science essential constants of physics. But in comparison programmers lots of programming other fundamental constants of physics that come from programming micro world, programming Avogadro regular connects micro world with programming macro world.