BARE-BONES GUIDE FOR A HP-42S CALCULATOR

RELEASE DATE:  9/5/037        DATE LAST REVISED:  9/4/07

    This is a bare-bones guide to get someone started who has one of these calculators and doesn’t know which buttons to push. Sorry, you won’t find a thing about programming here.

First of all, let's look at some of the functional keys.
1)  Red key:   The red key is pressed to shift from the function printed on the key to the function in red above the key. 
2)  Menus:  Notice that when certain functions such as MODES, DISP, MATRIX and other such selections are made, the top row of entry keys 
      is used for selecting a menu item.
3)  EXIT:  The exit key is used to get out of the menu listing or other  non-standard entries.
4)  MODES:  The modes key is used to select the type of display such as Degrees, Radians, Rectangular, and polar.  Press the Red key; then the 
      MODES key.  The top row of entry keys then becomes functional keys that correspond to the menu on the bottom line of the display.  5)  The
      DISP key is used for selecting the format for the number  display.  Examples are Scientific, Engineering,  and Fixed.
6)  Clear Key:  The clear key, the large left-pointing arrow, is used to clear the X-entry.  You can use the Red function of that key to clear other
      entries also.

A Few Words About RPN (Reverse Polish Notation):
    HP calculator gurus swear by RPN, but most of us prefer the regular algebraic entry method.  Actually, many calculators are sort of hybrid types that have a few RPN and the rest algebraic.  Anyway, an important feature of RPN is that you don't use parentheses.  Basically, you enter the numbers and then tell the calculator what mathematical operation you're going to perform AFTER you enter the numbers.  Let's go right to doing some arithmetic.

 Doing a Few Problems of Different Types:
1)  4 + 2:  Press the following keys:  4, ENTER, 2, +. You'll see the answer beside X.

2)  3 x 5:  3, ENTER, 5, x.  Notice that ENTER is NOT pressed after that last number.

3)  (7 + 5) ÷ (2 + 4):  7, ENTER, 5, +, 2, ENTER, 4, +, ÷ .  You'll notice that you enter divide in the last step. 

4)  4² :  4, ENTER,  Red, x² .   You can use this same procedure of entering a number and then the function with many of the keys, including these:  1/x, √x, LOG, LN, 10^x , e^x , and others.

5)  2⁵ : 2, ENTER, 5, y^x . 

6)  √(-9) :  3,+/-, ENTER, √x .  Notice that the answer is given as a complex number in rectangular form.

7)  6! (6 factorial):  6, ENTER, Red, PROB, N!

8)  6P3 (Permutations of 6 things taken 3 at a time):  6, ENTER, 3, Red,  PROB , COMB.   Other statistics are done in a similar way.

9)  i⁹⁸  :  1, Red, Complex, ENTER, 99, y^x .

10) Determinant of a  2 x 2 Matrix 1 ,2, 3 ,4:  Enter the dimension:   2, ENTER, 2, ENTER.  Red, MATRIX, NEW.  Enter data: 1, ENTER, XEQ, 2, ENTER, XEQ, 3, ENTER, XEQ, 4 ENTER, DET.  There may be other ways to do this, but this will work for any matrix.

 This is the basics.  There are many other functions which should be become obvious if you understand the method used for these.