Thank you for all the replies! Now I understand RPN is born for engineers XD

But school work is somewhat different. Here is my example.

To calculate the motion radius of a charge :

r=m*v/(q*B)

So I write the formula on my test paper first, then get my calculator, find out the value of variables from the question, and input them. Using natural display, all the values in the expression are just in there correct positions, corresponding to the formula.

*Edited: 5 May 2013, 4:34 a.m. after one or more responses were posted*

RPN is for sure born for it's small footprint in firmware/electronics. But it turned out to be useful beyond that.

In my opinion, in school it should be more important to deal with numbers rather than equations and their results. Understanding *how* an equation works is necessary, too.

RPN gives you all this: You need to understand a formula before entering it and you see all intermediate results. I do not want to elaborate this further, but e.g. in physics, the validity of an equation might be given only if some subterms are positive/negativ, larger zero or similar. You simply cannot see this easily with straightforward equation editing.

I started in life with a Casio, went over to RPN with the 32SII and never looked back. Is was pure luck, I had no idea about RPN or that this calculator did no real algebraic editing (except for the equation editor, of course).

Natural display is for lazy people just want to generate numbers, no matter how valid they are or what they are. You better use Excel for this.

IMHO RPN doesn't 'force' you to check the validity of your inputs. You can perfectly enter a negative value for an energy and get a result ;-( Even if I like the 'elegant' implementation of RPN for my own use, I would not restrict students to use Natural Display. I prefer a lot to have them thinking about the meaning of an equation and about what is a realistic guess rather to spend time on optimizing the use of registers for doing the computation.

I know, real men use RPN..., even use a slide rule from time to time ;-)