sin 33 =
So algebraic calculators are ambiguous because the many ways they work. RPN calculators are more
standard and so less ambiguous. The main key to understand how to use RPN in more complex
calculus is to realize that in RPN we make calculations from “inside” to “outside” instead of from left
to right. For example:
8 × ln [5+sin(40°)]
in RPN this is accomplished by
40 sin 5 + ln 8 ×
In RPN calculators, there is no operator precedence — operators are executed immediately and the
order of the calculations determines precedence. There is never any need for parentheses. In RPN we
can make any calculation we could do in algebraic devices and this is not only more elegant but also
more effective since there are less ambiguities and we use less key strokes. For example, my HP-33S,
which is both algebraic and RPN, is always in RPN mode. (Just to insert equations I think algebraic
mode is better) For more information on RPN, please see
http://www.hpmuseum.org/rpn.htm
2.2 Turn ON/OFF
To turn your HP-42 on press ON. The ON key is the same EXIT key. To turn your HP-42S off press
OFF. OFF is in the same key as EXIT and ON, and by OFF we mean you have to press the
orange key before pressing the EXIT key (which has “OFF” in orange above it). The orange key is
what in some other calculators is called “second function”. When you press this all keys turn into
what is written in orange above them.
Actually OFF is a redundancy since OFF can be only accessed by pressing first. But (as in the
HP-42S official manual) we will do this just to remember when we have to press or not. If you
press this key a second time all keys go back to the normal function.
2.3 Setting the display contrast
HP-42S, as most HP calculators, can set the display contrast by pressing at the same time ON and +-
or – .
2.4 Training RPN using HP-42S
Now that you have your 42S on try to do the following calculations:
Calculation Keystrokes
6 × (4 + 3) 4 ENTER 3 + 6 ×
6 +{8×[2+(4/3)]} 4 ENTER 3 / 2 + 8 × 6 +
IMPORTANT: For sake of simplicity sometimes we will use / instead of ÷.
2.5 Menus
Not all functions of HP-42S are visible above the keys. It has menus with access to many more
functions. The menus are
ALPHA MODES DISP CLEAR
SOLVER ∫f(x) MATRIX STAT
BASE CONVERT FLAGS PROB
CUSTOM PGM.FCN PRINT TOP.FCN
CATALOG
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