Appendix A: RPN and the Stack 235
File name: hp 12c pt_user's guide_English_HDPMF123E27 Page: 235 of 275
Printed Date: 2005/8/1
Dimension: 14.8 cm x 21 cm
Virtually every chain calculation you are likely to encounter can be done using
only the four stack registers. However, to avoid having to store an intermediate
result in a storage register, you should begin every chain calculation at the
innermost number or pair of parentheses and then work outward — just as you
would if you were doing the calculation manually (that is, using pencil and paper).
For example, consider the calculation of
3 [4 + 5 (6 + 7)]
If this calculation were done from left to right — as were the (simpler) examples
under Chain Calculations on page 23 and page 25 — you would have to enter
five
numbers into the calculator before doing the first operation possible (6 + 7).
But since the stack holds only four numbers, this calculation
cannot
be done
left-to-right. However, it can easily be done if you begin with the calculation in the
innermost pair of parentheses — again, (6 + 7).
Keystrokes
(RPN mode)
Display
6
\
7
+
13.00
Intermediate result of (6+7).
5
§
65.00
Intermediate result of 5 (6+7).
4
+
69.00
Intermediate result of [4 + 5(6 +
7)].
3
§
207.00
Final result: 3 [4 + 5 (6 + 7)].
Arithmetic Calculations with Constants
Because the number in the T-register remains there when the stack drops, this
number can be used as a constant in arithmetic operations. To place the constant
into the T-register, key it into the display (that is, into the X-register), then press
\
three times. This also places the constant in the Y and Z-registers. Each time
an arithmetic operation is then performed — using the constant in the Y-register
and a number keyed into the displayed X-register — the constant will be
“dropped” back into the Y-register.
Example:
The annual sales of solar engineering hardware your firm — currently
$84,000 — are projected to double each year for the next 3 years. Calculate the
annual sales for each of those years.
Keystrokes
(RPN mode)
Display
2
\\
\
2.00
Enters constant into Y, Z, and
T-registers.
