HP 12C Platinum Owner's Handbook Manual page 20

22 Section 1: Getting Started
The preceding example demonstrates how the HP 12C Platinum calculates just
as you would using pencil and paper (except a lot faster!):
ou do one
operation at a
time ...
Let's see this happening in a different type of calculation – one that involves
multiplying groups of two numbers and then adding the results. (This is the type
of calculation that would be required to total up an invoice consisting of several
items with different quantities and different prices.)
For example, consider the calculation of (3 × 4) + (5 × 6). If you were doing this
on paper, you would first do the multiplication in the first parentheses, then the
multiplication in the second parentheses, and finally add the results of the two
multiplications:
Your HP 12C Platinum calculates the answer in just the same way:
Keystrokes (RPN mode)
3\4§
5\6§
+
Notice that before doing step 2, you did not need to store or write down the result
of step 1: it was stored inside the calculator automatically. And after you keyed
in the 5 and the 6 in step 2, the calculator was holding two numbers (12 and 5)
inside for you, in addition to the 6 in the display. (The HP 12C Platinum can hold
a total of three numbers inside, in addition to the number in the display.) After
step 2, the calculator was still holding the 12 inside for you, in addition to the 30
in the display. You can see that the calculator holds the number for you, just as
you would have them written on paper, and then calculates with them at the
Display
Step 1: Multiply the numbers in the
12.00
first parentheses.
Step 2: Multiply the numbers in the
30.00
second parentheses.
Step 3: Add the results of the two
42.00
multiplications.
... and you see the
results of each
operation
immediately.