On Thu, 15 Aug 2013 16:43:41 +0100, Chris Angelico wrote: > A mole is as much a number (6e23) as the light year is a number > (9.5e15).
Not quite. A mole (abbreviation: mol) is a name for a specific number, like couple (2) or dozen (12) or gross (144), only much bigger: 6.02e23. And I can't believe I still remember that value :-) It's normally used only for atoms, ions or molecules, but in principle you could talk about anything. E.g. the population of the world is a mere 1.2e-14 mol. A light-year, on the other hand, is a dimensional quantity. Whereas mole is dimensionless, light-year has dimensions of Length, and therefore the value depends on the units you measure in: 1 light-year: = 3.724697e+17 inches = 0.30660139 parsec = 9.4607305e+12 kilometres etc. -- Steven -- http://mail.python.org/mailman/listinfo/python-list
