fx-3900PV Programs: Finance Factors

fx-3900PV Programs: Finance Factors

I’m revisiting the fx-3900Pv, which seems to be a hit. The last set of programs from May 3 of this year: https://edspi31415.blogspot.com/2025/05/casio-fx-3900pv-linear-system-poisson.html

Remember: When using the ENT (enter/input) command, we must enter a valid number and then the next step. The number that precedes ENT is not counted as a step and is not recorded.

Example: x + 9

In LRN (learn) mode (Mode EXP):

ENT (enter any number)

+

9

=

Casio fx-3900Pv: Simple Interest

maturity amount = principal amount * (1 + 0.01 * I%) * N ÷ 360

interest accrued = maturity amount – principal amount

I% = annual interest rate

N = number of days

The Act/360 method is used.

Code (23 steps):

ENT # enter principal amount (PV)

Kin 1

×

(

1

+

.

0

1

×

ENT # enter interest rate

×

ENT # enter number of days

÷

3

6

0

)

=

HLT # pause, display maturity amount

-

Kout 1

= # display interest accrued, end program

Example 1:

Inputs:

Principal Amount: 1,000.00

Rate: 5%

Number of Days: 30

Output (rounded to 2 decimal places)

Maturity Amount: 1,004.17

Interest Accrued: 4.17

Example 2:

Inputs:

Principal Amount: 360.00

Rate: 8%

Number of Days: 90

Output (rounded to 2 decimal places)

Maturity Amount: 367.20

Interest Accrued: 7.20

Casio fx-3900Pv: Compound Interest Factor with Compounding Periods

The following program calculates the compound interest factor:

factor = (1 + I% ÷ PYR) ^ (YRS × PVR)

where

I% = annual interest rate

PYR = payments per year (compounding periods)

YRS = number of years (N)

The factor is used in simple compound interest problems:

FV = PV × factor

where:

FV = future value

PV = present value

Code (19 steps):

(

1

+

.

0

1

×

ENT # enter interest rate

÷

ENT # enter payments per year

Kin 1

)

x^y

(

ENT # enter number of years

×

Kout 1

)

=

Example:

Find the compound interest interest factor for: I% = 5%, 12 payments a year, 4 years

Factor: 1.220895351

If an investor expects a $5,000.00 payoff, what should the investor pay?

PV = FV ÷ X

Keys: (with the answer from program displayed: [ 1/x ] [ × ] 5000 [ = ])

PV (rounded): 4,0953.36

Casio fx-3900Pv: Loan Annuity Factor

The following program calculates the loan annuity factor:

factor = ( ( 1 - ( 1 + I% ÷ PYR ) ^ (-YRS × PYR) ) ÷ ( I% ÷ PYR )

where

I% = annual interest rate

PYR = payments per year (compounding periods)

YRS = number of years (N)

The factor is used in loan problems without balloon payments, and assume that the payments occur at the end of each period (ordinary annuity):

PV = PMT × factor

where:

PV = present value

PMT = periodical payments

Code (30 steps):

ENT # enter interest rate

÷

ENT # enter payments per year

Kin 2

×

.

0

1

=

Kin 1 # K1 = I% ÷ PYR

ENT # enter number of years

×

Kout 2

=

Kin 2 # K2 = YRS × PYR = N

(

1

-

(

1

+

Kout 1

)

x^y

Kout 2

+/-

)

÷

Kout 1

=

Example:

A student buys a car at $35,619 (after taxes and fees). The student gets a six year loan at 5.7% and pays at the end of each month. What is the payment?

PMT = PV ÷ factor

where PV = 35619, I% = 5.7, PYR = 12 (monthly payments), YRS = 6

Running the program with inputs 5.7, 12, 6: 60.85819003

Payment: [ 1/x ] [ × ] 35619 [ = ]: 585.28 (rounded)

Casio fx-3900Pv: Sinking Fund Factor (Savings Account)

The following program calculates the sinking factor (used for savings accounts):

factor = ( (1 + I% ÷ PYR) ^ (YRS × PYR) – 1 ) ÷ (I% ÷ PYR)

The factor is used in determining the future value of savings plans with regular deposits made at the end of each period:

FV = PMT × factor

Code (29 steps):

ENT # enter interest rate

÷

ENT # enter payments per year

Kin 2

×

.

0

1

=

Kin 1 # K1 = I% ÷ PYR

ENT # enter the number years

×

Kout 2

=

Kin 2 # K2 = YRS × PYR

(

(

1

+

Kout 1

)

x^y

Kout 2

-

1

)

÷

Kout 1

=

Example:

A child’s parents opens up an account on the child’s first birthday. The parents contribute $200.00 per month for the next 18 years. The account pays a fixed rate of 3% per month. What is the value of the fund when the child turns 18?

Note: The account is opened on the child’s first birthday, hence 17 years pass.

FV = PMT × factor

where PMT = 100, I% = 3, PYR = 12, YRS = 17

Running the program with inputs 3, 12, 17: 265.69267

Future Value: [ × ] 200 [ = ]: 53,138.54 (rounded)

Until next time, stay safe and sane,

Eddie

All original content copyright, © 2011-2025. Edward Shore. Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited. This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author.

The content on this blog is 100% generated by humans. The author does not use AI engines and never will.

Retro Review: Casio fx-3900Pv

Retro Review:  Casio fx-3900Pv

Quick Facts

Model:  fx-3900Pv

Company:  Casio

Years:  late 1980s - early 1990s

Type:  Finance

Batteries: 1 x CR-2025

Display:  2 lines

Memory Registers:  1 independent with 6 constant registers

Operating System:  Algebraic 

Programming With Editing!

The fx-3900Pv has a programming module similar to the Casio fx-3600P, its many variations and Radio Shack EC-4004.   What separates the fx-3900Pv from the rest is the inclusion of an editing mode.   

The display has two lines.   The top line has all the mode indicators and program steps. The bottom line is the numeric display.  

We are not programming in the blind.  Yay!

Run Mode:   We execute programs in this mode. [ MODE ] [ . ]

Learn (LRN) Mode:  We enter programs from scratch.   [ MODE ] [ EXP ]

Edit Mode:  We edit programs stored in memory.  New entries are automatically inserted.   Program steps can be deleted by the [ SHIFT ] [ ↑ ] (CLR) key sequence.  [ MODE ] [ 0 ]

There are four program slots.  P3 is the shifted program of P1 and P4 the shift of P2.  

The programming commands available on the fx-3900Pv are:

ENT:  prompts the user for a number.  When entering a program, include a valid number after the ENT command.  The number entered after ENT is not counted as a program step.   

HLT:  Halts program execution.  In run mode, continue exection with the [ RUN ] key.

RTN:  Halts the program execution and returns to the first step.  The RTN instruction allows for repeated calculations.

x>0:  If the number in the display at the time is positive, the program returns the first step.   Otherwise, go to the next step.

x≤M:  If the number in the display is less than or greater than the value stored in memory M, go to the first step.  Otherwise, go to the next step.

A sample program:  

f(x) = x^3 - x^2 ÷ 4 + 1

We will use the first program slot.

P1:

SHIFT:  Min    (store in Memory M)

x^y

3 

-

MR   

SHIFT:  x^2

÷

4

+

1

=

f(2.2):  2.2 [ P1 ].   Result:  10.438

f(-1.9):  1. 9 [ +/- ] [ P1 ].  Result:  -6.7615

Integration  ∫dx

In the integration mode ( [ MODE ] [ 1 ]), we can designate one of the four program slots to approximate a definite integral using Simpson's Rule.  Memory M is used for x in f(x).   The program must start with a Min command and end in equals.  

To calculate the integral:

1.  Enter integral mode.

2.  Pick which program has f(x):  P1, P2, P3, or P4.

3.  Optional:  enter n to specify 2^n divisions, then press [ SHIFT ] [ RUN ].

4.  Enter the lower limit, press [ RUN ], enter upper limit, press [ RUN ].

Example:   ∫ x^3 - x^2 ÷ 4 + 1 dx for x = 1 to x = 5.  Use 16 divisions (n = 4)

[ MODE ] 1 [ P1 ]  (see the section above)

4 [ SHIFT ] [ RUN ]  (display: 16)

1 [ RUN ] 5 [ RUN ]

Result:  1.496666667 * 10^2

(2^8: 256 divisions returns 1.496666665 * 10^2 , after short while)

The integration updates the memory registers as such:

K1 = a

K2 = b

K3 = 2^n

K4 = f(a)

K5 = f(b)

K6 = integral

Other Features

The other modes of the fx-3900Pv are:

Mode 2:  LR.  Linear Regression.  Fits data to the line y = A x + B.

A:  slope

B:  intercept

r:  correlation

K1 = Σx^2

K2 = Σx

K3 = n

K4 = Σy^2

K5 = Σy

K6 = Σxy

Mode 4:  Degrees angle mode

Mode 5:  Radians angle mode

Mode 6:  Gradians angle mode

Mode 7:  Fix point display mode.  To round numbers to the fix point internally, execute the RND (round) command.  

 

Mode 8:  Scientific notation display mode

Mode 9:  Norm mode (floating point)

Registers

[ Kin ]:   Stores the number into any register K1 through K6.

[ Kout ]:  Recalls the value of K1 and K6.

The M register:  < Min >, [ M+ ],  < M- > , [ MR ].

Storage arithmetic:  [ Kin ] followed by [ + ], [ - ], [ × ], [ ÷ ]

Final Thoughts

The fx-3900Pv improves on the fx-3600P programming module by adding an editing mode. 

Missing from is the fractions and fraction-decimal conversions.   I would have loved to see other programming commands such as integer part, functional parts, and absolute value.   Other than that, the fx-3900Pv is a big improvement of the fx-3600P.

Casio Ledudu page of fx-3900Pv: 

https://casio.ledudu.com/pockets.asp?lg=eng&type=417

Eddie 

All original content copyright, © 2011-2023.  Edward Shore.   Unauthorized use and/or unauthorized distribution for commercial purposes without express and written permission from the author is strictly prohibited.  This blog entry may be distributed for noncommercial purposes, provided that full credit is given to the author.