Originally posted by Suzianne
Someone showed me an RPN calculator once and I swear, I thought he was April-fooling me.
Why would anyone put themselves through that?
RPN just makes things a bit simpler by not having to deal with parentheses, which can add up to quite a number in a complex calculation:
X=(R+(sqr(9*74.3) *(sin 12.5 degrees)+Pi*(87.3/23.5)))))
See all the parentheses in that calculation. RPN doesn't deal with those, instead doing calculations like we did in grade school:
See, no parentheses, just 2 numbers and an operator, so in RPN you hit 3, enter, hit 4, then hit +, now the screen reads 7
When you hit enter you are pumping up the numbers in a 'stack', a pretend stack of number bins you think of as vertically oriented, and numbers pump up and down depending on whether an operator button was hit, -,+,*, Square, stuff like that pumps numbers down the stack while 'enter' pumps them up, so if you hit 3, ent, ent, ent, then + the result is 6 on the screen and now there are just 3 sets of three, another +, and the bottom stack, the screen now says 9 and there are just 2 sets of three left, another + and the screen goes 12, with one 3 left in the stack, another + and now the screen shows 15 with no more three's in any of the pretend stacks.
The best way to visualize it is to just use the RPN calculator. When you get skilled at it, calculations flow much faster than having to deal with parentheses.