Ganymede, one of Jupiter’s 12 moons, has a diameter of 3200
miles. You can use the HP-67 to manually compute the area
of Ganymede. Merely press the following keys in order. For a
3200 mile diameter:
3 2 0 0
X
2
(g-shift 9 key)
π
(h-shift 2 key)
×
The result should be
32169908.78
You calculated the surface area of Ganymede! Now, if you
wanted the surface area of
each
of Jupiter’s moons, you could
repeat that procedure 67 times, using a different value for the
diameter
d
each time. An easier and faster method, however,
is to create a program that will calculate the surface area of a
sphere from its diameter, instead of pressing all the keys for
each moon.
Creating the Program.
A program is nothing more than the
series of keystrokes you would execute to solve the same
problem manually. Two additional operations, a
label
and a
return
are used to define the beginning and end of the
program.
Entering the Program.
To load the keystrokes of the
program into the calculator: