HP HP-21 - Page 16

14 Getting Started
Problems that are even more complicated can be solved in the
same simple manner, using the automatic storage of inter-
mediate results. For example, to solve (2 + 3) X (4 + 5) with a
pencil and paper, you would:
RQ+3)xM@4+)59
N’
First solve for the contents
of these parentheses. . . . . .. and then for these parentheses
. . and then you would multiply the two
intermediate answers together.
You work through the problem the same way with the HP-21,
except that you don’t have to write down intermediate answers
—the HP-21 remembers them for you.
First add 2 and 3:
Procedure Press Display
5
G+ x 4+5 EE3E
Then add 4 and S:
Procedure Press Display
5 9
Q3 x s 4ENED 5[+
Then multiply the intermediate answers together for the final
answer:
Procedure Press Display
s 9
23X @ty [
Notice that you didn’t need to write down the intermediate
answers from inside the parentheses before you multiplied—
the HP-21 automatically stored the intermediate results for you
and brought them out when it was time to multiply.