HP 12C User guide

HP 12C Platinum
Owner’s Handbook
and
Problem-Solving Guide
© Copyright 2003 Hewlett-Packard Development Company, L.P.

2
Introduction
About This Handbook
This HP 12C Platinum Owner’s Handbook and Problem-Solving Guide is
intended to help you get the most out of your investment in your HP 12C
Platinum Programmable Financial Calculator. Although the excitement of
acquiring this powerful financial tool may prompt you to set this handbook aside
and immediately begin “pressing buttons,” in the long run you’ll profit by
reading through this handbook and working through the examples it contains.
Following this introduction is a brief section called Making Financial
Calculations Easy—which shows you that your HP 12C Platinum does just that!
The remainder of this handbook is organized basically into three parts:
zPart I (sections 1 through 7) describes how to use the various financial,
mathematics, statistics, and other functions (except for programming)
provided in the calculator:
zSection 1 is about Getting Started. It tells you how to use the keyboard,
how to do simple arithmetic calculations and chain calculations, and
how to use the storage registers (“memories”).
zSection 2 tells you how to use the percentage and calendar functions.
zSection 3 tells you how to use the simple interest, compound interest,
and amortization functions.
zSection 4 tells you how to do discounted cash flow analysis, bond, and
depreciation calculations.
zSection 5 tells you about miscellaneous operating features such as
Continuous Memory, the display, and special function keys.
zSections 6 and 7 tell you how to use the statistics, mathematics, and
number-alteration functions.
zPart II (sections 8 through 11) describe how to use the powerful
programming capabilities of the HP 12C Platinum.
zPart III (sections 12 through 16) give you step-by-step solutions to
specialized problems in real estate, lending, savings, investment analysis,
and bonds. Some of these solutions can be done manually, while others
involve running a program. Since the programmed solutions are both self-
contained and step-by-step, you can easily employ them even if you don’t
care to learn how to create your own programs. But if you do start to create
your own programs, look over the programs used in the solutions: they
contain examples of good programming techniques and practices.

Introduction 3
zThe various appendices describe additional details of calculator operation
as well as warranty and service information.
zThe Function Key Index and Programming Key Index at the back of the
handbook can be used as a handy page reference to the comprehensive
information inside the manual
Financial Calculations in the United Kingdom
The calculations for most financial problems in the United Kingdom are
identical to the calculations for those problems in the United States – which are
described in this handbook. Certain problems, however, require different
calculation methods in the United Kingdom than in the United States. Refer to
Appendix G for more information.
For More Solutions to Financial Problems
In addition to the specialized solutions found in Sections 12 through 16 of this
handbook, many more are available in the optional HP 12C Platinum Solutions
Handbook. Included are solutions to problems in lending, forecasting, pricing,
statistics, savings, investment analysis, personal finance, securities, Canadian
mortgages, learning curves in manufacturing, and queuing theory. The solutions
handbook is available from your authorized HP dealer.

5
Contents
Introduction ...................................................................................... 2
About This Handbook..................................................................................... 2
Financial Calculations in the United Kingdom ................................................ 3
For More Solutions to Financial Problems...................................................... 3
Part I: Problem Solving................................................15
Section 1: Getting Started ................................................................... 16
Power On and Off......................................................................................... 16
Low-Power Indication ............................................................................. 16
The Keyboard ............................................................................................... 16
Keying in Numbers ................................................................................. 17
Digit Separators...................................................................................... 17
Negative Numbers.................................................................................. 17
Keying in Large Numbers ....................................................................... 18
The CLEAR Keys ................................................................................... 18
The RPN and ALG Keys......................................................................... 19
Simple Arithmetic Calculations in RPN Mode............................................... 19
Chain Calculations in RPN Mode ................................................................. 20
Storage Registers......................................................................................... 23
Storing and Recalling Numbers.............................................................. 24
Clearing Storage Registers .................................................................... 25
Storage Register Arithmetic.................................................................... 25
Section 2: Percentage and Calendar Functions............................ 27
Percentage Functions................................................................................... 27
Percentages ........................................................................................... 27
Net amount ............................................................................................. 27
Percent Difference.................................................................................. 28
Percent of Total ...................................................................................... 29
Calendar Functions ...................................................................................... 30
Date Format............................................................................................ 30
Future or Past Dates .............................................................................. 31
Number of Days Between Dates ............................................................ 32
Section 3: Basic Financial Functions............................................... 34
The Financial Registers................................................................................ 34
Storing Numbers Into the Financial Registers........................................ 34
Displaying Numbers in the Financial Registers ...................................... 34
Clearing the Financial Registers............................................................. 34
Simple Interest Calculations ......................................................................... 35
Financial Calculations and the Cash Flow Diagram ..................................... 36
The Cash Flow Sign Convention ............................................................ 38
The Payment Mode ................................................................................ 38
Generalized Cash Flow Diagrams.......................................................... 39

6 Contents
Compound Interest Calculations .................................................................. 41
Specifying the Number of Compounding Periods and the Periodic
Interest Rate ........................................................................................... 41
Calculating the Number of Payments or Compounding Periods ............ 41
Calculating the Periodic and Annual Interest Rates ............................... 45
Calculating the Present Value ................................................................ 46
Calculating the Payment Amount ........................................................... 48
Calculating the Future Value .................................................................. 49
Odd-Period Calculations......................................................................... 51
Amortization.................................................................................................. 54
Section 4: Additional Financial Functions ...................................... 58
Discounted Cash Flow Analysis: NPV and IRR............................................ 58
Calculating Net Present Value (NPV)..................................................... 59
Calculating Internal Rate of Return (IRR)............................................... 63
Reviewing Cash Flow Entries................................................................. 64
Changing Cash Flow Entries .................................................................. 66
Bond Calculations......................................................................................... 67
Bond Price .............................................................................................. 67
Bond Yield .............................................................................................. 68
Depreciation Calculations............................................................................. 68
Section 5: Additional Operating Features....................................... 70
Continuous Memory ..................................................................................... 70
The Display................................................................................................... 70
Status Indicators..................................................................................... 70
Number Display Formats........................................................................ 71
Scientific Notation Display Format.......................................................... 72
Special Displays ..................................................................................... 73
The ~Key................................................................................................ 74
The FKey ............................................................................................... 74
Arithmetic Calculations With Constants.................................................. 75
Recovering From Errors in Digit Entry.................................................... 75
Section 6: Statistics Functions .......................................................... 76
Accumulating Statistics................................................................................. 76
Correcting Accumulated Statistics................................................................ 77
Mean............................................................................................................. 77
Standard Deviation....................................................................................... 78
Linear Estimation.......................................................................................... 79
Weighted Mean ............................................................................................ 81
Section 7: Mathematics and Number-Alteration Functions ....... 82
One-Number Functions ................................................................................ 82
The Power Function ..................................................................................... 84

Contents 7
Part II: Programming....................................................85
Section 8: Programming Basics........................................................ 86
Why Use Programs? .................................................................................... 86
Creating a Program ...................................................................................... 86
Running a Program ...................................................................................... 87
Program Memory.......................................................................................... 88
Identifying Instructions in Program Lines................................................ 89
Displaying Program Lines....................................................................... 90
The i000 Instruction and Program Line 000..................................... 91
Expanding Program Memory.................................................................. 91
Setting the Calculator to a Particular Program Line ............................... 93
Executing a Program One Line at a Time .................................................... 94
Interrupting Program Execution.................................................................... 95
Pausing During Program Execution ....................................................... 95
Stopping Program Execution.................................................................. 98
Section 9: Branching and Looping................................................. 101
Simple Branching ....................................................................................... 101
Looping....................................................................................................... 101
Conditional Branching ................................................................................ 104
Section 10: Program Editing............................................................. 110
Changing the Instruction in a Program Line ............................................... 110
Adding Instructions at the End of a Program.............................................. 111
Adding Instructions Within a Program ........................................................ 112
Adding Instructions by Replacement .................................................... 112
Adding Instructions by Branching ......................................................... 113
Section 11: Multiple Programs......................................................... 117
Storing Another Program............................................................................ 117
Running Another Program.......................................................................... 119
Part III: Solutions........................................................121
Section 12: Real Estate and Lending ............................................. 122
Annual Percentage Rate Calculations With Fees....................................... 122
Price of a Mortgage Traded at a Discount or Premium .............................. 124
Yield of a Mortgage Traded at a Discount or Premium .............................. 125
The Rent or Buy Decision........................................................................... 127
Deferred Annuities...................................................................................... 131
Section 13: Investment Analysis..................................................... 134
Partial-Year Depreciation ........................................................................... 134
Straight-Line Depreciation .................................................................... 134
Declining-Balance Depreciation ........................................................... 137
Sum-of-the-Years-Digits Depreciation.................................................. 139
Full- and Partial-Year Depreciation with Crossover.................................... 141
Excess Depreciation................................................................................... 145
Modified Internal Rate of Return................................................................. 145

8 Contents
Section 14: Leasing............................................................................ 148
Advance Payments..................................................................................... 148
Solving For Payment ............................................................................ 148
Solving for Yield.................................................................................... 150
Advance Payments With Residual ............................................................. 152
Solving for Payment ............................................................................. 152
Solving For Yield .................................................................................. 154
Section 15: Savings............................................................................ 156
Nominal Rate Converted to Effective Rate................................................. 156
Effective Rate Converted to Nominal Rate................................................. 157
Nominal Rate Converted to Continuous Effective Rate.............................. 158
Section 16: Bonds............................................................................... 159
30/360 Day Basis Bonds ............................................................................ 159
Annual Coupon Bonds................................................................................ 161
Appendixes ................................................................ 165
Appendix A: RPN and the Stack .................................................... 166
Getting Numbers Into the Stack: The \ Key ......................................... 167
Termination of Digit Entry ..................................................................... 168
Stack Lift............................................................................................... 168
Rearranging Numbers in the Stack ............................................................ 168
The ~ Key........................................................................................ 168
The dKey.......................................................................................... 168
One-Number Functions and the Stack ....................................................... 169
Two-Number Functions and the Stack ....................................................... 169
Mathematics Functions......................................................................... 169
Percentage Functions........................................................................... 170
Calendar and Financial Functions .............................................................. 171
The LAST X Register and the F KEY ................................................... 172
Chain Calculations in RPN Mode ............................................................... 172
Arithmetic Calculations with Constants ...................................................... 173
Appendix B: Algebraic Mode (ALG) .............................................. 175
Simple Arithmetic calculations in ALG mode.............................................. 175
Keying in Negative Numbers (Þ)........................................................... 175
Chain Calculations in ALG mode................................................................ 176
Percentage Functions................................................................................. 176
Percent Difference................................................................................ 177
Percent of Total .................................................................................... 177
The Power Function ................................................................................... 178
Appendix C: More About L ......................................................... 179
Appendix D: Error Conditions ........................................................ 181
Error 0: Mathematics .................................................................................. 181
Error 1: Storage Register Overflow ............................................................ 181
Error 2: Statistics ........................................................................................ 182
Error 3: IRR ................................................................................................ 182

Contents 9
Error 4: Memory.......................................................................................... 182
Error 5: Compound Interest........................................................................ 182
Error 6: Storage Registers.......................................................................... 183
Error 7: IRR ................................................................................................ 183
Error 8: Calendar ........................................................................................ 184
Error 9: Service........................................................................................... 184
Pr Error ....................................................................................................... 184
Appendix E: Formulas Used ............................................................ 185
Percentage ................................................................................................. 185
Interest........................................................................................................ 185
Simple Interest...................................................................................... 185
Compound Interest............................................................................... 185
Amortization................................................................................................ 186
Discounted Cash Flow Analysis ................................................................. 187
Net Present Value ................................................................................ 187
Internal Rate of Return ......................................................................... 187
Calendar..................................................................................................... 187
Actual Day Basis .................................................................................. 187
30/360 Day Basis ................................................................................. 188
Bonds ......................................................................................................... 188
Depreciation ............................................................................................... 189
Straight-Line Depreciation .................................................................... 189
Sum-of-the-Years-Digits Depreciation.................................................. 190
Declining-Balance Depreciation ........................................................... 190
Modified Internal Rate of Return................................................................. 190
Advance Payments..................................................................................... 191
Interest Rate Conversions .......................................................................... 191
Finite Compounding ............................................................................. 191
Continuous Compounding.................................................................... 191
Statistics ..................................................................................................... 191
Mean..................................................................................................... 191
Weighted Mean .................................................................................... 192
Linear Estimation.................................................................................. 192
Standard Deviation............................................................................... 192
Factorial................................................................................................ 192
The Rent or Buy Decision........................................................................... 193
Appendix F: Battery, Warranty, and Service Information ........ 195
Battery ........................................................................................................ 195
Low-Power Indication ................................................................................. 195
Installing a New Battery........................................................................ 195
Verifying Proper Operation (Self-Tests) ..................................................... 196
Warranty ..................................................................................................... 198
Service........................................................................................................ 200
Potential For Radio/Television Interference (for U.S.A. Only) .................... 201
Temperature Specifications........................................................................ 201
Noise Declaration ....................................................................................... 201
Regulation applying to The Netherlands .................................................... 202

10 Contents
Appendix G: United Kingdom Calculations ................................ 203
Mortgages................................................................................................... 203
Annual Percentage Rate (APR) Calculations ............................................. 203
Bond Calculations....................................................................................... 204
Function Key Index ..................................................................... 205
Programming Key Index ............................................................. 208
Subject Index ............................................................................... 211

11
Making Financial
Calculations Easy
Before you begin to read through this handbook, let’s take a look at how easy
financial calculations can be with your HP 12C Platinum. While working
through the examples below, don’t be concerned about learning how to use the
calculator; we’ll cover that thoroughly beginning with Section 1.
Example 1: Suppose you want to ensure that you can finance your daughter’s
college education 14 years from today. You expect that the cost will be about
$6,000 a year ($500 a month) for 4 years. Assume she will withdraw $500 at the
beginning of each month from a savings account. How much would you have to
deposit into the account when she enters college if the account pays 6% annual
interest compounded monthly?
This is an example of a compound interest calculation. All such problems
involve at least three of the following quantities:
zn: the number of compounding periods.
zi: the interest rate per compounding period.
zP V : the present value of a compounded amount.
zPMT: the periodic payment amount.
zFV: the future value of a compounded amount.
In this particular example:
znis 4 years ×12 periods per year = 48 periods.
ziis 6% per year ÷ 12 periods per year = 0.5% per period.
zPV is the quantity to be calculated – the present value when the financial
transaction begins.
zPMT is $500.
zFV is zero, since by the time your daughter graduates she (hopefully!) will
not need any more money.
To begin, turn the calculator on by pressing the ;key. Then, press the keys
shown in the Keystrokes column below.1
Note: A battery symbol ( ) shown in the upper-left corner of the
display when the calculator is on signifies that the available battery power
is nearly exhausted. To install new batteries, refer to Appendix F.
1. If you are not familiar with the use of an HP calculator keyboard, refer to the description
on pages 16 and 17.

12 Making Financial Calculations Easy
The calendar functions and nearly all of the financial functions take some
time to produce an answer. (This is typically just a few seconds, but the
¼, !, L, and Sfunctions could require a half-minute or more.)
During these calculations, the word running flashes in the display to let
you know that the calculator is running.
Example 2: We now need to determine how to accumulate the required deposit
by the time your daughter enters college 14 years from now. Let’s say that she
has a paid-up $5,000 insurance policy that pays 5.35% annually, compounded
semiannually. How much would it be worth by the time she enters college?
In this example, we need to calculate FV, the future value.
Example 3: The preceding example showed that the insurance policy will
provide about half the required amount. An additional amount must be set aside
to provide the balance (21,396.61 – 10,470.85 = 10,925.76). Suppose you make
monthly payments, beginning at the end of next month, into an account that pays
Keystrokes Display
fCLEARHf2 0.00 Clears previous data inside the
calculator and sets display to show
two decimal places.
4gA 48.00 Calculates and stores the number of
compounding periods.
6gC 0.50 Calculates and stores the periodic
interest rate.
500P500.00 Stores periodic payment amount.
g× 500.00 Sets payment mode to Begin.
$–21,396.61 Amount required to be deposited.a
a Don’t be concerned now about the minus sign in the display. That and other details will
be explained in Section 3.
Keystrokes (RPN mode) Display
fCLEARG–21,396.61 Clears previous financial data
inside the calculator.
14\2§w 28.00 Calculates and stores the number of
compounding periods.
5.35\2z¼ 2.68 Calculates and stores the periodic
interest rate.
5000Þ$ –5000.00 Stores the present value of the
policy.
M10,470.85 Value of policy in 14 years.

Making Financial Calculations Easy 13
6% annually, compounded monthly. What payment amount would be required in
order to accumulate $10,925.75 in the 14 years remaining?
Example 4: Suppose you cannot find a bank that currently offers an account
with 6% annual interest compounded monthly, but you can afford to make
$45.00 monthly payments. What is the minimum interest rate that will enable
you to accumulate the required amount?
In this problem, we do not need to clear the previous financial data inside the
calculator, since most of it is unchanged from the preceding example.
This is only a small sampling of the many financial calculations that can now be
done easily with your HP 12C Platinum. To begin learning about this powerful
financial tool, just turn the page.
Keystrokes Display
fCLEARG10,470.85 Clears previous financial data
inside the calculator.
14gA 168.00 Calculates and stores the number of
compounding periods.
6gC 0.50 Calculates and stores the periodic
interest rate.
10925.76M10.925.76 Stores the future value required.
g 10.925.76 Sets payment mode to End.
P–41.65 Monthly payment required.
Keystrokes Display
45ÞP –45.00 Stores payment amount.
¼0.42 Periodic interest rate.
12§5.01 Annual interest rate.

Part I
Problem Solving

16
Section 1
Getting Started
Power On and Off
To begin using your HP 12C Platinum, press the ;key1. Pressing ;again
turns the calculator off. If not manually turned off, the calculator will turn off
automatically 8 to 17 minutes after it was last used.
Low-Power Indication
A battery symbol ( ) shown in the upper-left corner of the display when the
calculator is on signifies that the available battery power is nearly exhausted. To
replace the batteries, refer to Appendix F.
The Keyboard
Many keys on the HP 12C Platinum perform two or even three functions. The
primary function of a key is indicated by the characters printed in white on the
upper face of the key. The alternate function(s) of a key are indicated by the
characters printed in gold above the key and the characters printed in blue on the
lower face of the key. These alternate functions are specified by pressing the
appropriate prefix key before the function key.
:
Throughout this handbook, references to the operation of an alternate function
appear as only the function name in a box (for example, “The Lfunction …”).
References to the selection of an alternate function appear preceded by the
1. Note that the ;key is lower than the other keys to help prevent its being pressed
inadvertently.
zTo specify the alternate function printed in
gold above a key, press the gold prefix key
(f), then press the function key.
zTo specify the primary function printed on
the upper face of a key, press the key alone.
zTo specify the alternate function printed in
blue on the lower face of a key, press the
blue prefix key (g), then press the
function key.

Section 1: Getting Started 17
appropriate prefix key (for example, “Pressing fL …”). References to the
functions shown on the keyboard in gold under the bracket labeled “CLEAR”
appear throughout this handbook preceded by the word “CLEAR” (for example,
“The CLEAR Hfunction …” or “Pressing fCLEARH…”).
If you press the for gprefix key mistakenly, you can cancel it by pressing
fCLEAR X. This can also be pressed to cancel the ?, :, and i
keys. (These keys are “prefix” keys in the sense that other keys must be pressed
after them in order to execute the corresponding function.) Since the Xkey is
also used to display the mantissa (all 10 digits) of a displayed number, the
mantissa of the number in the display will appear for a moment after the X
key is released.
Pressing the for gprefix key turns on the corresponding status indicator – f
or g– in the display. Each indicator turns off when you press a function key
(executing an alternate function of that key), another prefix key, or
fCLEAR X.
Keying in Numbers
To key a number into the calculator, press the digit keys in sequence, just as if
you were writing the number on paper. A decimal point must be keyed in (using
the decimal point key) if it is part of the number unless it appears to the right of
the last digit.
Digit Separators
As a number is keyed in, each group of three digits to the left of the decimal
point is automatically separated in the display. When the calculator is first turned
on after coming from the factory – or after Continuous Memory is reset – the
decimal point in displayed numbers is a dot, and the separator between each
group of three digits is a comma. If you wish, you can set the calculator to
display a comma for the decimal point and a dot for the three-digit separator. To
do so, turn the calculator off, then press and hold down the .key while you
press ;. Doing so again sets the calculator to use the original digit separators
in the display.
Negative Numbers
To make a displayed number negative – either one that has just been keyed in or
one that has resulted from a calculation – simply press Þ(change sign). When
the display shows a negative number – that is, the number is preceded by a minus
sign – pressing Þremoves the minus sign from the display, making the
number positive.

18 Section 1: Getting Started
Keying in Large Numbers
Since the display cannot show more than 10 digits of a number, numbers greater
than 9,999,999,999 cannot be entered into the display by keying in all the digits
in the number. However, such numbers can be easily entered into the display if
the number is expressed in a mathematical shorthand called “scientific notation.”
To convert a number into scientific notation, move the decimal point until there
is only one digit (a nonzero digit) to its left. The resulting number is called the
“mantissa” of the original number, and the number of decimal places you moved
the decimal point is called the “exponent” of the original number. If you moved
the decimal point to the left, the exponent is positive; if you moved the decimal
point to the right (this would occur for numbers less than one), the exponent is
negative. To key the number into the display, simply key in the mantissa, press
Æ(enter exponent), then key in the exponent. If the exponent is negative,
press Þafter pressing Æ.
For example, to key in $1,781,400,000,000, we move the decimal point 12
places to the left, giving a mantissa of 1.7814 and an exponent of 12:
Numbers entered in scientific notation can be used in calculations just like any
other number.
The CLEAR Keys
Clearing a register or the display replaces the number in it with zero. Clearing
program memory replaces the instructions there with gi000. There are
several clearing operations on the HP 12C Platinum, as shown in the table
below:
Keystrokes Display
1.7814Æ12 1.7814 12 1,781,400,000,000 entered in
scientific notation.
Key(s) Clears:
ODisplay and X-register.
fCLEAR²Statistics registers (R1through R6), stack
registers, and display.
fCLEARÎProgram memory (only when pressed in
Program mode).
fCLEARGFinancial registers.
fCLEARHData storage registers, financial registers,
stack and LAST X registers, and display.

Section 1: Getting Started 19
The RPN and ALG Keys
The calculator can be set to perform arithmetic operations in either RPN
(Reverse Polish Notation) or ALG (Algebraic) mode.
In reverse polish notation (RPN) mode, the intermediate results of calculations
are stored automatically, hence you do not have to use parentheses.
In algebraic (ALG) mode, you perform addition, subtraction, multiplication, and
division in the traditional way.
To select RPN mode: Press f] to set the calculator to RPN mode. When the
calculator is in RPN mode, the RPN status indicator is lit.
To select ALG mode: Press f[ to set the calculator to ALG mode. When
the calculator is in ALG mode, the ALG status indicator is lit.
Example
Suppose you want to calculate 1 + 2 = 3.
In RPN mode, you enter the first number, press the \key, enter the second
number, and finally press the arithmetic operator key: +.
In ALG mode, you enter the first number, press +, enter the second number,
and finally press the equals key: }.
In RPN mode and algebraic mode, the results of all calculations are listed.
However, in RPN mode only the results are listed, not the calculations.
Most examples in this manual (except those in Appendix B) assume that RPN
mode is selected. Some examples will also be correct if you are in ALG mode.
Simple Arithmetic Calculations in RPN Mode
In RPN mode, any simple arithmetic calculation involves two numbers and an
operation – addition, subtraction, multiplication, or division. To do such a
calculation on your HP 12C Platinum, you first tell the calculator the two
numbers, then tell the calculator the operation to be performed. The answer is
calculated when the operation key (+,-,§, or z) is pressed.
The two numbers should be keyed into the calculator in the order they would
appear if the calculation were written down on paper left-to-right. After keying
in the first number, press the \key to tell the calculator that you have
completed entering the number. Pressing \separates the second number to
be entered from the first number already entered.
RPN mode ALG mode
1 \2 +1 +2 }

20 Section 1: Getting Started
In summary, to perform an arithmetic operation:
1. Key in the first number.
2. Press \to separate the second number from the first.
3. Key in the second number.
4. Press +,-,§, or zto perform the desired operation.
For example to calculate 13 ÷ 2, proceed as follows:
Notice that after you pressed \, two zeroes appeared following the decimal
point. This is nothing magical: the calculator’s display is currently set to show
two decimal places of every number that has been entered or calculated. Before
you pressed \, the calculator had no way of knowing that you had completed
entering the number, and so displayed only the digits you had keyed in. Pressing
\tells the calculator that you have completed entering the number: it
terminates digit entry. You need not press \after keying in the second
number because the +,-,§, and zkeys also terminate digit entry. (In fact,
all keys terminate digit entry except for digit entry keys – digit keys, ., Þ,
and Æ– and prefix keys – f, g,?, :, and (.)
Chain Calculations in RPN Mode
Whenever the answer has just been calculated and is therefore in the display, you
can perform another operator with this number by simply keying in the second
number and then pressing the operation key: you need not press \ to separate
the second number from the first. This is because when a number is keyed in
after a function key (such as +,-,§,z, etc.) is pressed, the result of that
prior calculation is stored inside the calculator – just as when the \key is
pressed. The only time you must press the \key to separate two numbers is
when you are keying them both in, one immediately following the other.
The HP 12C Platinum is designed so that each time you press a function key in
RPN mode, the calculator performs the operation then – not later – so that you
see the results of all intermediate calculations, as well as the “bottom line.”
Keystrokes (RPN mode) Display
13 13. Keys the first number into the
calculator.
\13.00 Pressing \separates the second
number from the first.
22. Keys the second number into the
calculator.
z6.50 Pressing the operation key
calculates the answer.

Section 1: Getting Started 21
Example: Suppose you’ve written three checks without updating your
checkbook, and you’ve just deposited your paycheck for $1,053.00 into your
checking account. If your latest balance was $58.33 and the checks were written
for $22.95, $13.70, and $10.14, what is the new balance?
Solution: When written down on paper, this problem would read
58.33 – 22.95 – 13.70 – 10.14 + 1053
Keystrokes (RPN mode) Display
58.33 58.33 Keys the first number.
\58.33 Pressing \separates the second
number from the first.
22.95 22.95 Keys in the second number.
-35.38 Pressing -subtracts the second
number from the first. The
calculator displays the result of this
calculation, which is the balance
after subtracting the first check.
13.70 13.70 Keys in the next number. Since a
calculation has just been
performed, do not press \; the
next number entered (13.70) is
automatically separated from the
one previously in the display
(35.38).
-21.68 Pressing -subtracts the number
just entered from the number
previously in the display. The
calculator displays the result of this
calculation, which is the balance
after subtracting the second check.
10.14-11.54 Keys in the next number and
subtracts it from the previous
balance. The new balance appears
in the display. (It’s getting rather
low!)
1053+1,064.54 Keys in the next number – the
paycheck deposited – and adds it to
the previous balance. The new,
current balance appears in the
display.

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!):
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:
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 5and the 6in 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
Keystrokes (RPN mode) Display
3\4§12.00 Step 1: Multiply the numbers in the
first parentheses.
5\6§30.00 Step 2: Multiply the numbers in the
second parentheses.
+42.00 Step 3: Add the results of the two
multiplications.
Youdoone
operation at a
time ...
... and you see the
results of each
operation
immediately.