# Turn On/off; Setting The Display Contrast; Training Rpn Using Hp-42s; Menus - HP -42S Manual

An alternative: hp-42s calculator and free42 simulator for palmos.

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

## 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
orange key before pressing the EXIT key (which has "OFF" in orange above it). The orange
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
HP-42S official manual) we will do this just to remember when we have to press
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
6 × (4 + 3)
6 +{8×[2+(4/3)]}
IMPORTANT: For sake of simplicity sometimes we will use / instead of ÷.

Not all functions of HP-42S are visible above the keys. It has menus with access to many more
ALPHA
SOLVER
BASE
CUSTOM
CATALOG
Keystrokes
4 ENTER 3 + 6 ×
4 ENTER 3 / 2 + 8 × 6 +
MODES
DISP
∫f(x)
MATRIX
CONVERT
FLAGS
PGM.FCN
PRINT
http://www.hpmuseum.org/rpn.htm
OFF
we mean you have to press the
CLEAR
STAT
PROB
TOP.FCN
key is
first. But (as in the
or not. If you
+-