On Friday 06 February 2009 13:50:49 Martin Vlietstra wrote: > Should we be talking about the rule of 1000 or the rule of 10^(NM) where N > is the power of the unit concerned and M is an integer of our choice. In > most cases = 1, so we can set M = 3. > > In the case of volumes, N = 3, so if we set M =1, we still get to the rule > of 1000. > > However in the case of areas, N = 2, so the rule of 1000 is not possible. > If we set M = 2, we get large steps and we also loose out on the rule of > 1000². If however we set M = 1, then we have smaller steps, but we can > still use the rule of 1000². This suggests that areas should be mm², cm², > dm², m², a, ha, km² etc.
I think it should be the rule of 1000 regardless of the power of the unit. If we use the rule of 1000 for mass, but the rule of 100 for area, then for mass per area (which could be paper density or agricultural yield), we get the rule of 10, which is more prone to calculation error. Pierre
