HP 12c Owners Manual

							  Section 1: Getting Started  21 
 
File name: hp 12c_users guide_English_HDPMBF12E44  Page: 21 of 209   
Printered Date: 2005/7/29    Dimension: 14.8 cm x 21 cm 
 
Keystrokes Display  
- 
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. 
The preceding example demonstrates how the hp 12c 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: 
  
						

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Your hp 12c calculates the answer in just the same way: 
Keystrokes 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. 
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 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 proper 
time, just as you would yourself.
*  But with the hp 12c, you don’t need to write 
down the results of an intermediate calculation, and you don’t even need to 
manually store it and recall it later. 
By the way, notice that in step 2 you needed to press \
 again. This is simply 
because you were again keying in two numbers immediately following each other, 
without performing a calculation in between. 
To check your understanding of how to calculate with your hp 12c, try the 
following problems yourself. Although these problems are relatively simple, more 
complicated problems can be solved using the same basic steps. If you have 
difficulty obtaining the answers shown, review the last few pages. 
00 . 77 ) 6 5 ( ) 4 3 (=+×+ 
25 . 0
) 38 14 () 14 27 (
=
+− 
13 . 0
21 16 35
=
+ + 
                                                 
* Although you don’t need to know just how these numbers are stored and brought back at just 
the right time, if you’re interested you can read all about it in Appendix A. By gaining a more 
complete understanding of the calculator’s operation, you’ll use it more efficiently and 
confidently, yielding a better return on the investment in your hp 12c.  
						

							  Section 1: Getting Started  23 
 
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Storage Registers 
Numbers (data) in the hp 12c are stored in memories called “storage registers” or 
simply “registers.” (The singular term “ memory” is sometimes used in this 
handbook to refer to the entire collection of storage registers.) Four special 
registers are used for storing numbers during calculations (these “stack registers” 
are described in Appendix A), and another (called the “LAST X” register) is used 
for storing the number last in the display before an operation is performed. In 
addition to these registers into which numbers are stored automatically, up to 20 
“data storage” registers are available for manual storage of numbers. These data 
storage registers are designated R
0 through R9 and R.0 through R.9. Fewer registers 
are available for data storage if a program has been stored in the calculator (since 
the program is stored in some of those 20 registers), but a minimum of 7 registers 
is always available. Still other storage registers — referred to as the “financial 
registers” — are reserved for numbers used in financial calculations. 
Storing and Recalling Numbers 
To store the number from the display into a data storage register: 
1. Press ? (store). 
2.  Key in the register number: 0 through 9 for registers R
0 through R9, or .0 
through .9 for registers R
.0 through R.9. 
Similarly, to recall a number from a storage register into the display, press :
 
(recall), then key in the register number. This copies the number from the storage 
register into the display; the number remains unaltered in the storage register. 
Furthermore, when this is done, the number previously in the display is 
automatically held inside the calculator for a subsequent calculation, just as the 
number in the display is held when you key in another number.   
Example:
 Before you leave to call on a customer interested in your personal 
computer, you store the cost of the computer ($3,250) and also the cost of a 
printer ($2,500) in data storage registers. Later, the customer decides to buy six 
computers and one printer. You recall the cost of the computer, multiply by the 
quantity ordered, and then recall and add the cost of the printer to get the total 
invoice. 
Keystrokes Display  
3250?1 
3,250.00 Stores the cost of the computer in R1. 
2500?2 
2,500.00 Stores the cost of the printer in R2. 
; 
  Turns the calculator off.  
						

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Later that same day … 
Keystrokes Display  
; 
2,500.00 Turns the calculator back on. 
:1 
3,250.00 Recalls the cost of the computer to the 
display. 
6§ 
19,500.00Multiplies the quantity ordered to get 
the cost of the computers. 
:2 
2,500.00 Recalls the cost of the printer to the 
display. 
+ 
22,000.00Total invoice. 
Clearing Storage Registers 
To clear a single storage register — that is, to replace the number in it with 
zero — merely store zero into it. You need not clear a storage register before 
storing data into it; the storing operation automatically clears the register before 
the data is stored. 
To clear all storage registers at once — including the financial registers, the stack 
registers, and the LAST X register — press f
CLEARH
.
* This also clears the 
display. 
All storage registers are also cleared when Continuous Memory is reset (as 
described on page 70). 
Storage Register Arithmetic 
Suppose you wanted to perform an arithmetic operation with the number in the 
display and the number in a storage register, then store the result back into the 
same register without altering the number in the display. The hp 12c enables you 
to do all this in a single operation: 
1. Press ?. 
2. Press +, -, §, or z to specify the desired operation. 
3.  Key in the register number.   
When storage register arithmetic is performed, the new number in the register is 
determined according to the following rule: 
 
                                                 
* CLEARH is not programmable.  
						

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Storage register arithmetic is possible with only registers R0 through R4. 
Example:
 In the example on page 20, we updated the balance in your 
checkbook. Let’s suppose that because data is stored indefinitely in your 
calculator’s Continuous Memory, you keep track of your checking account balance 
in the calculator. You could use storage register arithmetic to quickly update the 
balance after depositing or writing checks. 
Keystrokes Display  
58.33?0 
58.33 Stores the current balance in register 
R
0. 
22.95?-0 
22.95 Subtracts the first check from the 
balance in R
0. Note that the display 
continues to show the amount 
subtracted; the answer is placed only 
in R
0. 
13.70?-0 
13.70 Subtracts the second check. 
10.14?-0 
10.14 Subtracts the third check. 
1053?+0 
1,053.00 Adds the deposit. 
:0 
1,064.54 Recalls the number in R0 to check the 
new balance.  
						

							 
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  Section 2 
Percentage and Calendar 
Functions 
Percentage Functions 
The hp 12c includes three keys for solving percentage problems: b
, à
, and Z
. 
You don’t need to convert percentages to their decimal equivalents; this is done 
automatically when you press any of these keys. Thus, 4% need not be changed to 
0.04; you key it in the way you see and say it: 4b
. 
Pe rc e n t a g e s  
To find the amount corresponding to a percentage of a number: 
1.  Key in the base number. 
2. Press \. 
3.  Key in the percentage. 
4. Press b. 
For example, to find 14% of $300: 
Keystrokes Display  
300 
300. Keys in the base number. 
\ 
300.00 Pressing \
 separates the next 
number entered from the first number, 
just as when an ordinary arithmetic 
calculation is performed. 
14 
14. Keys in the percentage. 
b 
42.00 Calculates the amount. 
If the base number is already in the display as a result of a previous calculation, 
you should not press \
 before keying in the percentage — just as in a chain 
arithmetic calculation.  
						

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Net Amount 
A net amount — that is, the base amount plus or minus the percentage amount — 
can be calculated easily with your hp 12c, since the calculator holds the base 
amount inside after you calculate a percentage amount. To calculate a net amount, 
simply calculate the percentage amount, then press =
 or -
. 
Example: 
You’re buying a new car that lists for $13,250. The dealer offers you 
a discount of 8%, and the sales tax is 6%. Find the amount the dealer is charging 
you, then find the total cost to you, including tax. 
Keystrokes Display  
13250\ 
13,250.00Keys in the base amount and 
separates it from the percentage. 
8b 
1,060.00 Amount of discount. 
- 
12,190.00Base amount less discount. 
6b 
731.40 Amount of tax (on $12,190). 
= 
12,921.40Total cost: base amount less discount 
plus tax. 
Percent Difference 
To find the percent difference between two numbers: 
1.  Key in the base number. 
2. Press \ to separate the other number from the base number. 
3.  Key in the other number. 
4. Press à. 
If the other number is greater than the base number, the percent difference will be 
positive. If the other number is less than the base number, the percent difference 
will be negative. Therefore, a positive answer indicates an increase, while a 
negative answer indicates a decrease.   
If you are calculating a percent difference over time, the base number is typically 
the amount occurring first. 
Example:
 Yesterday your stock fell from 58
1/2 to 531/4 per share. What is the 
percent change?
 
Keystrokes Display  
58.5\ 
58.50 Keys in the base number and 
separates it from the other number. 
53.25 
53.25 Keys in the other number. 
à 
–8.97 Nearly a 9% decrease.  
						

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The à
 key can be used for calculations of the percent difference between a 
wholesale cost and a retail cost. If the base number entered is the wholesale cost, 
the percent difference is called the markup; if the base number entered is the retail 
cost, the percent difference is called the margin. Examples of markup and margin 
calculations are included in the hp 12c Solutions Handbook. 
Pe rc e n t  of  To t a l  
To calculate what percentage one number is of another: 
1.  Calculate the total amount by adding the individual amounts, just as in a 
chain arithmetic calculation.   
2.  Key in the number whose percentage equivalent you wish to find. 
3. Press Z. 
Example: 
Last month, your company posted sales of $3.92 million in the U.S., 
$2.36 million in Europe, and $1.67 million in the rest of the world. What 
percentage of the total sales occurred in Europe?
 
Keystrokes Display  
3.92\ 
3.92 Keys in the first number and separates 
it from the second. 
2.36+ 
6.28 Adds the second number. 
1.67+ 
7.95 Adds the third number to get the total. 
2.36 
2.36 Keys in 2.36 to find what percentage 
it is of the number in the display. 
Z 
29.69 Europe had nearly 30% of the total 
sales. 
The hp 12c holds the total amount inside after a percent of total is calculated. 
Therefore, to calculate what percentage another amount is of the total: 
1.  Clear the display by pressing O. 
2.  Key in that amount. 
3. Press Z again. 
For example, to calculate what percent of the total sales in the preceding example 
occurred in the U.S. and what percent occurred in the rest of the world: 
Keystrokes Display  
O3.92Z 
49.31 The U.S. had about 49% of the total 
sales. 
O1.67 Z 
21.01 The rest of the world had about 21% 
of the total sales.  
						

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To find what percentage a number is of a total, when you already know the total 
number: 
1.  Key in the total number.   
2. Press \ to separate the other number from the total number. 
3.  Key in the number whose percentage equivalent you wish to find. 
4. Press Z. 
For example, if you already knew in the preceding example that the total sales 
were $7.95 million and you wanted to find what percentage of that total occurred 
in Europe: 
Keystrokes Display  
7.95\ 
7.95 Keys in the total amount and separates 
it from the next number. 
2.36 
2.36 Keys in 2.36 to find what percentage 
it is of the number in the display. 
Z 
29.69 Europe had nearly 30% of the total 
sales. 
Calendar Functions 
The calendar functions provided by the hp 12c — D
 and Ò
 — 
can handle 
dates from October 15, 1582 through November 25, 4046. 
Date Format 
For each of the calendar functions — and also for bond calculations (E
 and 
S
) 
— the calculator uses one of two date formats. The date format is used to 
interpret dates when they are keyed into the calculator as well as for displaying 
dates. 
Month-Day-Year.
 To set the date format to month-day-year, press gÕ
. To 
key in a date with this format in effect: 
1.  Key in the one or two digits of the month. 
2.  Press the decimal point key (.). 
3.  Key in the two digits of the day. 
4.  Key in the four digits of the year. 
Dates are displayed in the same format. 
For example, to key in April 7, 2004: 
Keystrokes Display  
4.072004 
4.072004   
						

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Day-Month-Year.
 To set the date format to day-month-year, press gÔ
. To 
key in a date with this format in effect: 
1.  Key in the one or two digits of the day. 
2.  Press the decimal point key (.). 
3.  Key in the two digits of the month. 
4.  Key in the four digits of the year. 
For example, to key in 7 April, 2004: 
Keystrokes Display  
7.042004 
7.042004  
When the date format is set to day-month-year, the D.MY
 status indicator in the 
display is lit. If D.MY
 is not lit, the date format is set to month-day-year. 
The date format remains set to what you last specified until you change it; it is not 
reset each time the calculator is turned on. However, if Continuous Memory is reset, 
the date format is set to month-day-year. 
Future or Past Dates 
To determine the date and day that is a given number of days from a given date: 
1.  Key in the given date and press \. 
2.  Key in the number of days. 
3.  If the other date is in the past, press Þ. 
4. Press gD. 
The answer calculated by the D
 function is displayed in a special format. The 
numbers of the month, day, and year (or day, month, and year) are separated by 
digit separators, and the digit at the right of the displayed answer indicates the 
day of the week: 1 for Monday through 7 for Sunday.
* 
Example:
 If you purchased a 120-day option on a piece of land on 14 May 
2004, what would be the expiration date?
 Assume that you normally express 
dates in the day-month-year format. 
Keystrokes Display  
gÔ 
7.04 Sets date format to day-month-year. 
(Display shown assumes date 
remains from preceding example. 
The full date is not now displayed 
because the display format is set to 
show only two decimal places, as 
described in Section 5.) 
                                                 
* The day of the week indicated by the D function may differ from that recorded in history 
for dates when the Julian calendar was in use. The Julian calendar was standard in England 
and its colonies until September 14, 1752, when they switched to the Gregorian calendar. 
Other countries adopted the Gregorian calendar at various times.