# HP 12c (platinum) - Keyboard Functions

**ON** Turns the calculator off and exits the program, retaining continuous memory.

**f** Press to access gold functions.

**g** Press to access blue functions.

**PREFIX** Displays mantissa of number in the displayed X-register.

**ENTER** Pushes number in display into the stack.

**CHS** Changes sign of number or exponent of 10 in displayed X-register.

**EEX** Enter exponent. After pressing, next numbers keyed in are exponents of 10.

**0-9** Digits used for keying in numbers and display formatting. To format the display, press f then a digit representing the number of decimal places desired in the display.

**.** Decimal point. Also used for display formatting. Pressing f . sets the calculator to display numbers in scientific notation.

**CLX** Clears contents of displayed X-register to zero.

**+,-,x,/** Arithmetic operators. Computes Y-register operator X-register and places the result in X-register after the stack is dropped.

**STO** Store. Followed by number key, decimal point and number key, or top-row financial key, stores displayed number in storage register specified. Also used to perform storage register arithmetifc.

**RCL** Recall. Followed by number key, decimal point and number key, or top-row financial key, recalls value from storage register specified into the displayed X-register.

**REG** Clears contents of stack (X,Y,Z,T), all storage registers, statistical registers, and financial registers. Leaves program memory untouched; not programmable.

**%** Computes x% of y and retains the y value in the Y-register.

DLT % Computes percent of change between number in Y-register and number in displayed X-register.

%T Computes percent that x is of number in Y-register.

D.MY Sets date format to day-month-year; not programmable. (Example: 2.121995 is December 2, 1995) When this mode is set, the D.MY status indicator in the display is lit.

M.DY Sets date format to month-day-year; not programmable. (Example: 2.121995 is February 12, 1995)

DATE Changes a date in the Y-register by the number of days in the X-register and displays day of week. Sunday is 7. Monday is 1.

DYS Computes the number of days between two dates in the Y- and X-registers. The answer shown in the display is the actual number of days between the two dates, including leap days (the extra days occuring in leap years), if any. In addition, the HP-12C also calculates the number of days between the two dates on the basis of a 30-day month. This answer is held inside the calculator; to display it, press x>

FIN Clears contents of financial registers.

BEG Sets payment mode to Begin for compound interest calculations involving payments. When this mode is set, the BEGIN status indicator in the display is lit.

END Sets payment mode to End for compound interest calculations involving payments.

INT Calculates simple interest. Key in number of days, then press n. Key in annual interest rate, then press i. Key in the principal amount, then press CHS PV. Negative, due to the cash flow sign convention. Press f INT to calculate and display the interest accrued on a 360-day basis. If you want to display the interest accrued on a 365-day basis, press R x>

, and PV can be entered in any order.

n Stores or computes number of periods in financial problem.

12x Multiplies a number in displayed X-register by 12 and stores the resulting value in n.

i Stores or computes interest rate per compounding period.

12/ Divides number in displayed X-register by 12 and stores the resulting value in i.

PV Stores or computes present value (initial cash flow) of a financial problem.

PMT Stores or computes payment amount.

FV Stores or computes future value (final cash value) of a financial problem.

AMORT Amortizes x number of periods using values stored in PMT, i, PV, and the display. Updates values in PV and n. Press f CLEAR FIN to clear the financial registers. Enter the periodic interest rate, using i or 12/. Enter the amount of the loan (the principal), using PV. Key in the periodic payment, them press CHS PMT. (The sign of PMT must be negative, in accordance with the cash flow sign convention.) Press g BEG or (for most direct reduction loans) g END to set the payment mode. Key in the number of payments to be amortized. Press f AMORT to display the amount from those payments applied toward interest. Press x>

NPV Calculates the net present value of up to 20 uneven cash flows and initial investment using values stored with CFo, CFj, and Nj. Press f CLEAR REG to clear the financial and storage registers. Key in the amount of the initial investment, press CHS if that cash flow is negative, then press g CFo. If there is no initial investment, press 0 g CFo. Key in the amount of the next cash flow, press CHS if the cash flow is negative, then press g CFj. If the cash flow amount is zero in the next period, press 0 g CFj. Repeat last step for each cash flow until all have been entered. Enter the interest rate, using i or 12/. Press f NPV.

IRR Calculates the internal rate of return (yield) for up to 20 uneven cash flows and initial investment using values stored with CFo, CFj, Nj. Enter the cash flows using the method described for NPV. Press f IRR.

The internal rate of return is shown in the display and also stored in the i register. If you get an Error 3 message in the display, you can try the procedure outlined in Error Conditions regarding an Error 3 message to resolve this condition by entering a new guess for IRR.

CFo Initial cash flow. Stores contents of displayed X-register in R0, initializes n to zero, sets N0 to 1. Used at the beginning of a discounted cash flow problem.

CFj Cash flow j. Stores contents of X-register in Rj, increments n by 1, sets Nj to 1. Used for all cash flows except the initial cash flow in a discounted cash flow problem.

Nj Stores the number (from 1 to 99) of times each cash flow occurs as Nj. Assumes 1 unless otherwise specified.

PRICE Calculates bond price, given desired yield to maturity. Enter the desired yield (as a percentage) using i. Enter the annual coupon rate (as a percentage), using PMT. Key in settlement (purchase) date, then press ENTER. Key in the maturity (redemption) date. Press f PRICE. The price is shown in the display and also is stored in the PV register. The interest accrued since the last interest date is held inside the calculator: to display the interest, press x>

YTM Calculates yield to maturity, given bond price. Enter the quoted price (as a percent of par: HP-12C uses a par value of 100 for bond calculations), using PV. Enter the annual coupon rate (as a percentage), using PMT. Key in the settlement (purchase) date, then press ENTER. Key in the maturity (redemption) date. Press f YTM.

SL Calculates depreciation using straight-line method. For depreciation calculations, enter the original cost of asset, using PV. Enter the salvage value of asset, using FV. Enter the expected useful life of the asset (in years), using n. SL, SOYD, and DB each place the amount of depreciation in the display. To display the remaining depreciable value (the book value less the salvage value) after the depreciation has been calculated, press x>

SOYD Calculates depreciation using sum-of-the-years digits method. Enter cost of asset, salvage value of asset, and expected useful life of asset, as described for SL.

DB Calculates depreciation using declining-balance method. Enter cost of asset , salvage value of asset, and expected useful life of asset, as described for SL. Enter the declining-balance factor (as a percentage), using i. For example 1.25 times the straight-line rate– 125 percent declining-balance– would be entered as 125 i.

SUM Clears statistical storage registers R1 through R6 and stack registers.

SUM+ Accumulates statistics using numbers from X- and Y-registers in storage registers R1 through R6. Key the y-value into the display. Press ENTER. Key the x-value into the display. Press SUM+. Each time you press SUM+, the calculator does the following: The number in R1 is increased by 1, and the result is copied into the display. The x-value is added to the number in R2. The square of the x-value is added to the number in R3. The y-value is added to the number in R4. The square of the y-value is added to the number in R5. The product of the x- and y-values is added to the number in R6.

SUM- If you discover you have entered data incorrectly, the accumulated statistics can easily be corrected: If the incorrect data point or data pair has just been entered and SUM+ has been pressed, press g LST x g SUM-. If the incorrect data point or data pair is not the most recent one entered, key in the incorrect data point or data pair again as if it were new, but press g SUM- instead of SUM+. These operations cancel the effect of the incorrect data point or data pair. You can then enter the data correctly, using SUM+, just as if it were new.

x bar Computes mean (average) of x-values and y-values using accumulated statistics. The mean of the x-values appears in the display after the function key is pressed; to display the mean of the y-values, press x>

x bar w Computes weighted average of y-(item) and x-(weight) values using accumulated statistics.

s Computes sample standard deviations of x- and y-values using accumulated statistics. The standard deviation of x-values appears in the display after s is pressed; to display the standard deviation of the y-values, press x>

y hat,r Linear estimate (X-register), correlation coefficient (Y-register). Fits a line to a set of (x,y) data pairs enterd using SUM+, then extrapolates this line to estimate a y-value (y hat) for a given x-value. Also computes strength of linear relationship (r) among that set of (x,y) data pairs.

x hat,r Linear estimate (X-register), correlation coefficient (Y-register). Fits a line to a set of (x,y) data pairs enterd using SUM+, then extrapolates this line to estimate a x-value (x hat) for a given y-value. Also computes strength of linear relationship (r) among that set of (x,y) data pairs.

SQRT Computes square root of number in displayed X-register.

y^x Raises number in Y-register to power of number in X-register.

1/x Computes reciprocal of number in displayed X-register.

n! Computes factorial [n*(n-1)…3*2*1] of number in displayed X-register.

e^x Natural antilogarithm. Raises e (approximately 2.718281828) to power of number in displayed X-register.

LN Computes natural logarithm (base e) of number in displayed X-register.

RND Rounds mantissa of 10 digit number in X-register to match the display.

INTG Leaves only the integer portion of number in displayed X-register by truncating fractional portion.

FRAC Leaves only the fractional portion of number in displayed X-register by truncating integer portion.

x>

R Rolls down contents of stack for viewing in displayed X-register.

LST x Recalls number displayed before the previous operation back into the displayed X-register.

P/R Program/Run. Toggles into and out of program mode. Automatically sets program to line 00 when returning to Run mode. When in program mode, the PRGM status indicator in the display is lit.

MEM Memory map. Describes the current allocation of memory; the number of lines allotted to program memory and the number of available data registers.

R/S Run/Stop. Begins execution of a stored program. Stops execution if program is running. If multiple programs are held in program memory, you can execute a specific program by positioning the calculator to the program line where that program starts by using the GTO function. Then pressing R/S will begin execution at that program line. When executed as a program, usually to display intermediate results, pressing R/S will resume execution of the program at the line just after the R/S instruction.

SST Single step. Displays line number and contents of next program memory line. If held down, in PRGM mode, displays line number and contents of all program memory lines, one at a time. In RUN mode, executes instruction, displays result, and moves to next line when released.

GTO Go to. Followed by a two digit number, in RUN mode positions calculator to that line in program memory. No instructions are executed. In PRGM mode, pressing g GTO . followed by two digit keys sets the calculator to the program line specified. As an instruction in a program, (omitting the . enters the keystroke sequence as a program instruction) causes calculator to branch to the specified line number next, and resumes program execution from there. The decimal point is not necessary if the calculator is in RUN mode, but it is necessary if the calculator is in PRGM mode.

PSE Pause. Stops program execution for about 1 second and displays contents of X-register, then resumes program execution.

BST Back Step. Displays, in PRGM mode, line number and contents of previous program memory line. In RUN mode, displays line number of previous program memory line when pressed; displays original contents of X-register when released. No instructions are executed.

x<=y

x=0 Conditional. x<=y tests number in X-register against that in Y-register. x=0 tests number in X-register against zero. If true, calculator continues execution at next program memory line. If false, calculator skips next line before resuming execution.