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.

Python: Financial Functions (2nd Edition)

Python:  Financial Functions (2nd Edition)

This is an update to the python file, which I first released on May 17, 2020:

https://edspi31415.blogspot.com/2020/05/numworkscasio-micropythonpython.html

I am able to transfer and test the python file to a Numworks calculator through the online editor, and TI-84 Plus CE Python through the TI Connect CE.  Because only the math module is used, the python file can be run in most, if not all calculators with Python, as well as Python 3.  

What is included?

*  time value of money calculations

*  net present value and internal rate of return

*  net present value (xnpv) and internal rate of return (xirr) when periods between flows are not consistent, a 365 day-year is assumed

*  simple interest:  calculating interest, total, and solving for principal

*  profit calculations: cost-sell-markup

*  adding sales tax

*  percent change

*  present and future value uniform stream factors

*  compound interest calculations of a single stream:  solve for present value, future value, number of periods, and periodic interest

*  days between dates

*  specific applications:  monthly payment, PITI, qualifying loan amount, sinking fund, expressing a list of amounts as a percent of the sum, prorating an amount among a list of flows

Download the Python file and the instructions (pdf file) here:

https://drive.google.com/file/d/1l7Xg9dM-RHfekKkU7A1Wjay76-yVc56S/view?usp=sharing

Size: about 3,800 bytes.  

Eddie

All original content copyright, © 2011-2020.  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. 

Numworks/Casio MicroPython/Python: Financial Functions

Numworks/Casio MicroPython/Python:  Financial Functions 

My first python script for the Numworks calculator:  finance.py

Great calculator and glad I finally have one. 

Introduction

The following scripts creates the user functions for the following financial functions:

pchg(old, new):  Returns the percent change between two numbers
Example:  pchg(1400,2600) returns 85.71

taxlplus(amt, tax): Adds the tax rate to an amount. amt + tax%.  Results are rounded up to 2 decimal places.
Example:  taxplus(59,9.5) returns 64.6

uspv(n,i):  Takes n (number of payments) and i (periodic interest rate) and calculates the uniform present value factor.  PV = PMT * USPV.  Future value is assumed to be 0.
Example:  n = 36 payments, i = 0.25%.  uspv(36,0.25) returns 34.39

usfv(n,i):  Takes n (number of payments) and i (periodic interest rate) and calculates the uniform future value factor.  FV = PMT * USFV.  Present value is assumed to be 0.
Example:  n = 36 payments, i = 0.25%.  usfv(36,0.25) returns 37.62

mopmt(yrs,rate,loan):  Calculates the monthly payment of a loan with monthly payments.  Payments are assumed to be due at the end of each month.   Results are rounded to up to 2 decimal places. 
Example:  Loan of $238,000 for 30 years at 4.28% annual rate.  mompt(30,4.28,238000) returns 1175.0

annrate(ppy,cpy,rate):  Calculates the equivalent annual rate given ppy (payments per year), cpy (compounding payments per year), rate (estimated periodic rate).
Example:  ppy = 12, cpy = 2, periodic rate = 0.74%.   annrate(12,2,0.74) returns 9.0459

Source for annrate:
Roger F. Farish and The Staff of the Texas Instruments Learning Center.  Calculator Analysis for Business and Finance.  Texas Instruments, Inc.  1977.  ISBN 0-89512-015-1

sinkfund(yrs,rate,pymt):  Calculates the balance of a sink fund (savings account)  of monthly deposits.   Number of years and the annual interest rate are needed.  Deposits are assumed to be due at the end of each month.   Results are rounded to up to 2 decimal places. 
Example:  Monthly deposits of $400.00 for 5 years, at a rate of 2.9%.  sinkfund(5,2.9,400) returns 25793.77

piti(yrs,rate,loan,tax,insur):   Calculates the monthly payment of a mortgage given:  the term of the loan in years (yrs), the annual interest rate (rate), the mortgage (loan), the annual property tax (tax), and the annual property insurance (insur).  Payments are assumed to be due at the end of each month.  Results are rounded to up to 2 decimal places.
Example:  piti(30,3.3,160000,1349,240) returns 833.15

qualinc(inc,debt,taxins,rate,yrs):  Calculates the qualifying amount given the following parameters:  monthly income (inc), monthly debt payments (debt), monthly proper taxes and insurance (taxins), interest rate (rate), and term of the mortgage in years (yrs).   Mortgage payments are assumed to be due at the end of each month.   The standard debt:income ratio of 28:36 is used.  Results are rounded to up to 2 decimal places.
Example:  qualinc(4485,375,126.83,5.30) returns 207288.6


Python Script: finance.py

# 2020-04-12 EWS

from math import *

# percent change
def pchg(old,new):
  pch=(new-old)/old*100
  return pch

# add sales tax  
def taxplus(amt,tax):
  total=amt*(1+0.01*tax)
  return round(total,2)

# uniform pv factor pv=pmt*uspv
def uspv(n,i):
  factor=(1-(1+0.01*i)**(-n))/(0.01*i)
  return factor

# uniform fv factor fv=pmt*usfv
def usfv(n,i):
  factor=((1+0.01*i)**n-1)/(0.01*i)
  return factor
  
# monthly payment
def mopmt(yrs,rate,loan):
  pymt=loan/uspv(yrs*12,rate/12)
  return round(pymt,2)
  
# equivalent annual rate
def annrate(ppy,cpy,rate):
  irate=cpy*100*((1+0.01*rate)**(ppy/cpy)-1)
  return irate
  
# sinking fund
def sinkfund(yrs,rate,pymt):
  sink=pymt*usfv(yrs*12,rate/12)
  return round(sink,2)

# piti
def piti(yrs,rate,loan,tax,insur):
  pymt=loan/uspv(yrs*12,rate/12)+(tax+insur)/12
  return round(pymt,2)

# qualifying income 28:36 ratio
def qualinc(inc,debt,taxins,rate,yrs):
  a=min(inc*0.36-debt,inc*0.28)-taxins
  qual=a*uspv(yrs*12,rate/12)
  return round(qual,2)

Eddie

All original content copyright, © 2011-2020.  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.