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oierpa · 12-03-2021, 03:43 PM

Hi all.
I'm new in this forum and quite a new HP calculator user.
When I discovered HP world (at university) I was fascinating on it, but during ’90 years I had not a lot of money to change calculator and HP was really expensive. My first programmable calculator (in fact) was an old CASIO FX850-P, I still have it since 1989 and still work, this calculator had a BASIC programming interface, really simple.
During lockdown I bought a 50g and I tried to start programming it and I found really difficult. I also have a HP 35s bought to keep it in office, with this calculator I understood RPN mode, I like it and I started to program this calculator, I found it really simple and intuitive, so I decided to move to an upgrade, the 50g.
I’m sure that my difficult are due to difference between a basic like language (typical of Casio calculator) and User RPL, but I found this language so strange that it’s extremely difficult for me find some solution.

One of my tipical problem is this:
I’m approaching with a simple financial formula to calculate a periodical amount of a loan, formula is simple: ( I can solve it with a simple formula in the equation editor, but I would solve it with a program to made some practice.
I had no problem to input initial data: amount of a loan, interest rate, number or yearly period (12 in this case), number of years.
I need to calculate:

montly amount;
total amount;
interest.

Formula I use (is not important now), is R=C+((t/100/12)/(1-(1+t/100/12)^(-A*12)), where:

R: montly amount;
t: annual interest rate;
A: number of years.

My problem is to calculate the three quantities above and show them in the display. I can only calculate one (montly amount, or total amount, or interest), but not the other because I can’t recall intermediate calculation and display it correctly.
I'm locked in this kind of problem, I'm sure that is stupid, but I've no idea to unlok my mind now.
Thanks in advance for any help.