Inline functions inside the 10BA Financial Calculator for Android

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Background

Many of the functions in the 10BA Professional Financial Calculator takes more then one number as input; for instance, the calendar function [ΔDYS]  that calculates the number of days between two dates understandably takes two numbers as input: the first number as date1, and the second number as date2. Another common example is the percent change function [%CHG] that calculates the change in percentage between two numbers. Something like the percent of change from 10 to 15 is 50%.

 

Traditional keystrokes v. Inline function format

To calculate the percent of change from 1250 to 1600 the keystrokes are traditionally like below, which gives 28% as answer.

1250 [INPUT]  1600 [%CHG] 

In addition to doing it like the above, any two- or three-number function can also be calculated using the inline format without using [INPUT] as follows.

1250 [%CHG] 1600 [=]

To calculate the number of days between 29 January 2025 and 14 August 2025 (if using the month-day-year format they are January 29 2025 and  August 14 2025) you can either use the traditional keystrokes using the [INPUT] key like below.

29.012025 [INPUT] 14.082025 [ΔDAYS] 

and the keystrokes using the inline format without the [INPUT] key are like below.

29.012025 [ΔDAYS] 14.082025 [=] 

The answer is 197 days. (Note if you use the month-day-year format, the above dates are to be entered as 1.292025 and 8.142025).

 

So which one to use?

An advantage of using the inline format is input validation. In the above inline keystrokes, as soon as you tap [ΔDAYS] the calculator will check and make sure that the first number that you type is a valid date. If you incidentally type 29.292025 [ΔDAYS] the calculator will immediately display an error and not let you proceed.

Compared this with the traditional keystrokes 29.292025 [INPUT] 14.2025 [ΔDAYS] where it initially accepts the two numbers without complaining and display the error message only after you tap [ΔDAYS] . This is because at first it does not know what you want to do with 29.292025 [INPUT] 14.2025. Only after you tap [ΔDAYS] it knows that you want to do a calendar function and it must check the validity of the two numbers.

However, many people like the traditional keystrokes because they like using the [INPUT] key to clearly separate the numbers. So which keystrokes you want to use is a matter of preference.

Inline function inside 10BA Financial Calculator for Android

19 Comments

  • Jiten

    Excellent…
    Also please show me the calculation on 20 year armotised schedule payment on 200K loan at 4.25 %
    And then making 25000 extra payment to the principle in every year after 5 year
    With keeping constant regular payment of
    1238.14
    Now I want to know how soon my loan payoff sooner.
    Thank you
    Please show the mathod of inputing the data.
    Thank you for your help

  • HERMAN LUKITO

    Hi this is one way to do it.

    First, calculate the regular monthly payment (which you already did) using the keystrokes below.

    [CLR TVM]
    240 [N]
    200,000 [PV]
    4.25 [I/YR]
    12 [SHIFT DOWN] [P/YR]
    [PMT]

    We get the monthly payment PMT = -1,238.47.

    Next, we need find the remaining loan balance after five years or after 60 payments.

    60 [N]
    [FV]

    The result is FV = -164,629.07. (You can also use the built-in amortization schedule function [AMORT] to find the loan balance after 60 payments. Result will differ by a few cents due to the standard rounding mechanism used to generate the amortization schedule).

    Then there are extra payments of 25,000 per year. We need to calculate the monthly equivalent.

    12 [N]
    25,000 [FV]
    4.25 [I/YR]
    0 [PV]
    [PMT] .

    We get PMT = -2,043.06.

    So basically with extra payments of 25,000 per year in addition to regular monthly payments of 1,238.47 you are making monthly payments of 2,043.06 + 1,238.47 = 3,281.53.

    Finally we need to calculate how long it will take to pay off the the remaining loan balance of 164,629.07 with monthy payments of 3,281.53.

    164,629.07 [PV]
    4.25 [I/YR]
    – 3,281.53 [PMT]
    0 [FV]
    [N].

    We get N = 55.33 months or 4 years + 8 months.

    Therefore with this payment scheme it will take 9 years + 8 months to pay off the loan. Note you will be making 4 extra payments of 25,000 per year, plus the last extra which is not fully 25,000.

    Please read the article “Determining Loans with Extra Annual Payments” in the link below. We are not affiliated with HP in any way.

    https://support.hp.com/us-en/document/bpia5026

  • Brad

    Hi, I am really enjoying this calculator, but I can’t seem to figure out how to run a calculation where the deposit frequency (e.g. monthly) is different from the compounding frequency (e.g. daily).

    I have P/YR = payments/yr, but I don’t see how to do C/YR. Can you please confirm how to do this?

    • HERMAN LUKITO

      The [C/YR] function will be implemented in a future release of the calculator.

      In the current version you need to use interest rate conversion functions so interest rate matches the payment period.

      As an illustration, suppose you have an account that pays 6% interest rate compounded quarterly and you deposit $100 into the account every month. Find the future value after 10 years.

      [BLUE SHIFT] [CLR TVM]
      4 [YELLOW SHIFT] [P/YR]
      6 [YELLOW SHIFT] [NOM%]
      [YELLOW SHIFT] [EFF%]

      The effective rate is 6.14%. Now find the equivalent nominal rate if payments are monthly.

      12 [YELLOW SHIFT] [P/YR]
      [YELLOW SHIFT] [NOM%]

      You will get the equivalent nominal rate of 5.97%. Now find the future value.

      100 [+/-] [PMT]
      10 [x] 12 [N]
      [FV]

      The future value after 10 years is $16,361.50.

  • Gabriel

    Nice but I can’t use it!
    There is no Usor Manual to know how to use it. I have been trying for hours to find … but just can’t find, if thwere is one.

    I guess I’ll have to go with HP caculators they all have a User Manual.

    • HERMAN LUKITO

      Each functions/keys in the calculator has a cheatsheet that describes what it does, and one or two examples.

      To view the cheatsheet tap the question mark icon at top right, then tap the function/key.

      For instance, to find out what [FV] is tap the question mark at top right, then tap [FV].

  • Mario

    I am having trouble with the simplest PV FV calculation: for a 2 year 5% annual interest FV calculation. I enter N=2, I/YR = 5, PV= 100, and I get -100.835!!! I should be getting -110.25…

    Can you please help?

    • HERMAN LUKITO

      Since you are doing annual compounding, you need to set the number of payments per year variable [P/YR] to 1. Currently it is equal to 12 which is the default value.

      Here [P/YR] is the yellow function on the [PMT] key. So keystrokes are below.

      [BLUE SHIFT] [CLR TVM]
      1 [YELLOW SHIFT] [P/YR]
      2 [N]
      5 [I/YR]
      100 [PV]
      [FV]

      The future value is -110.25.

      For further info on [P/YR], simply tap the question mark at top right then tap [YELLOW SHIFT][P/YR], similarly with other functions/keys.

  • Rob Krenitsky

    Terrific app! Only disappointment is no RPN data input logic option. Is that something you would consider incorporating? I’m a career long HP12C user and RPN is the way my brain has become wired! Love your app though and may put the effort into rewiring.
    BTW, I will happily pay your $2 asking price.
    Thanks ,
    Rob

    • HERMAN LUKITO

      Lamento que, no momento, ainda não tenhamos recursos para traduzir o produto para outros idiomas; no entanto, faremos todos os esforços para tornar isso possível e, uma vez que tenhamos os recursos necessários, o português será o primeiro idioma para o qual será traduzido. Obrigado.

  • Nicholas Corona

    Any way you can do 365/360 amortization with this calculator? I really like the calculator, but also would like to see RPN

    • HERMAN LUKITO

      The current version of the calculator does not directly support 365/360 amortization. For this type of calculations you need to do interest rate conversion first as you might already knew.

      As of the RPN, yes we do have plans to incorporate this in a future release of the calculator. And in case you are interested, at present we have a simple RPN calculator with basic functionalities. You could check it out from the Google Play store at the link below.

      https://play.google.com/store/apps/details?id=pro.segitiga.s3rpn

  • Dave

    Calculation of Canadian Mortgage (Rate compounded semi-annually and paid monthly)
    First ensure ” Annual” and “End” appear in the status indicator.

    (green key) CLR TVM
    300 N (example for 25 years # of months)
    2.69 I/R (example – posted rate 2.69%)
    -100,000 PV – Mortgage amount as a negative (example -100,000)
    2 (yellow key) P/YR
    (yellow key) EFF
    12 (yellow key) P/YR
    (yellow key) NOM%
    =
    I/R
    PMT (Will show monthly pmt which should be 457.48 for this example)

    RCL (yellow key) AMORT (will create schedule which can be exported.)

    OR optionally after PMT you can
    1 input 24 (or any # to 300) then “=” will give Princ, Int, Bal totals

  • Melva Viva Grace

    Hi,
    Can you please help me with this calculation:
    FV = 100
    N = 5
    PMT = 12
    I%yr = 10%
    PV?
    The correct answer for PV is 107.6 but I always get 112.13.
    I’ve never get the correct answer for TVM questions.
    Do I miss some steps?

    Thank you
    Best,
    Melva

    • HERMAN LUKITO

      The payment mode setting is currently set at the end of the period, and your TVM problem requires payment at the beginning of the period.

      Note the string “END” on the calculator display indicating the current payment mode.

      To change payment mode to the beginning of the period, tap [BLUE SHIFT] [BEG/END] to toggle it. Here [BEG/END] is the blue function on [MAR] the rightmost key on the second row. Note the string “BEG” on the display indicating payment mode is set at the beginning of the period.

      After you set the correct payment mode, repeat the keystrokes you will get the correct answer 107.58.

      100 [FV]
      5 [N]
      12 [PMT]
      10 [I/YR]
      1 [YELLOW SHIFT] [P/YR]
      [PV]

    • HERMAN LUKITO

      Note for all TVM calculations all relevant variables are [N], [I/YR], [PV], [PMT], [FV], [P/YR], and [BEG/END].

      If you do not enter any values into or set any of the above variables, previous stored values (which might come from previously unrelated calulcations) will be used thus give incorrect result. This is applicable to all financial calculators regardless of make and model.

      For instance, if your TVM problem does not involve any payments, you need to explicitly store 0 into [PMT] and don’t assume that [PMT] already contains zero.

      Also pay attention to the Payments per Year [P/YR] variable, which is the yellow function on [PMT]. If you are doing annual payment, store 1 into [P/YR]. For monthly payments store 12 into [P/YR] and so on.

      Tap the question mark at top right, then tap a key for examples on keystrokes. E.g. tap the question mark at top right, then tap [PMT] on examples on how to calculate [PMT].

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