10  The HP-25 Means Painless Programming 
II 
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Area 
of 
Ganymede 
in 
square miles. 
Programmed Problem Solving 
If 
you wanted the surface areas 
of 
each 
of 
Jupiter
's 
12 
moons, 
you could 
repeat 
the above procedure 
12 
times. 
However, 
you 
might wish to  write a 
program 
that 
would calculate 
area 
of 
a 
sphere from  its  diameter,  instead 
of 
pressing all  the  keys for 
each 
moon. 
To 
calculate 
the 
area 
of 
a sphere using a program, you should 
first 
write 
the program, then you must 
record 
the program into 
the  calculator,  and  finally  you 
run 
the  program  to  calculate 
the answer. 
Writing the Program: 
You 
have already written 
it! 
A program 
is 
nothing more than the series 
of 
keystrokes 
you would 
execute 
to solve the 
same 
problem manually. 
Recording the Program: 
To 
record the 
keystrokes 
of 
the 
pro-
gram into the calculator: 
I. 
Slide  the 
PRGM-RUN 
switch 
PRGM~RUN 
to 
PRGM 
(program). 
PRG.., 
2.  Press 
II 
a  to clear the calculator. 
3. 
Press 
the following keys 
in 
order. (When you are  record-
ing a program, the display gives you information 
that 
you 
will  find  l/seful  later, but you 
can 
ignore the  display for 
now.) 
:} 
II 
These 
keys are the same keys you pressed to 
solve  the problem manually. 
H3 
~ 
Running 
the 
Program: 
Slide 
the 
PRGM-RUN 
switch 
PRGM 
.wmJ!J 
RUN 
back 
to 
RUN 
and press 
in 
order 
~ 
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