Hi Eddie,

I think it's a good idea to familiarize others with the benefits of RPN. However, some errors should be removed:

RPN uses **one** stack that consists of (usually) four **registers** X, Y, Z and T.

Your text however says:

*"Typically, RPN calculators uses ***four** stacks, named X, Y, **Y, and Z**."

Instead, it should read:

"Typically, RPN calculators use a stack consisting of four registers, named X, Y, Z, and T."

So, X, Y, Z and T are four *registers* (not stacks), each register stacked on top of the other. That's why the whole arrangement is called a stack.

Maybe an RPN novice will get the idea behind the stack more quickly if the examples show intermediate results. For instance like this (example #5):

2 [1/x] 0,5000

3 [ENTER] 7 [÷] 0,4286

[+] 0,9286

25 [ENTER] 64 [÷] 0,3906

[sqrt] 0,6250 ; use the symbol instead - there is no key labelled "sqrt"

[-] 0,3036 ; do not omit the leading zero - it's displayed

Re. Enter: about 30 years ago I had a book on RPN that described the idea behind the ENTER key in two-argument calculations this way: ENTER is required to tell the calculator that you have completed number entry. So 5 ENTER 3 enters two numbers five and three instead of a 53, thus separating the 5 from the 3. This also means that an ENTER is *not* required before or after a numeric operation, before or after a STO or RCL, before or after Pi, etc.: in all these cases it's clear that the current number resp. result is complete, and everything keyed in next will belong to a new number. So the first ENTER in your example #5 is obsolete since after 1/x the calculator knows that the result (1/2) is complete and the following 3 belongs to a new number.

This idea was very helpful for me in the first weeks after I aquired my brand new 34C back then. Maybe you will find it useful as well. I really like the idea to help new RPN users the way you intended. That's why I suggest these improvements. :-)

Dieter