PC-1211, PC-1250, etc. TVM

[robve]

(06-08-2024 06:19 PM)dm319 Wrote:  

(06-07-2024 12:27 AM)Albert Chan Wrote:  lua> tvm_begin(40, nil, 900, -400, -1000)
0.8000000000098451

Ah! That makes sense. I was thrown by the 80% exact. I guess this problem is very affected by the number of digits of precision the calculator can store on that interest rate.

I added two of the problems to my bank of TVM problems.

Indeed, 80% is exact in 10 places. I'm working with 10 digits only on the SHARPs.
I've added an annotation to my old post to explain.

If you want another bewildering TVM problem:
B=1 (begin mode)
N=40
PV=900
PMT=1000
FV=-1000
What's the interest rate?

In the real world this makes no sense, i.e. getting rich for nothing in return, but mathematically it is a valid TVM problem to solve. Try it on a calculator. Is the rate you get a whole number?

- Rob