(04-30-2019 07:44 PM)rprosperi Wrote: IIRC, even using the provided formulas will produce slightly different results than manually using the built-in TVM, probably because the TVM code has some twekas for corner cases, and preserves accuracy in iterative calculations.

The main issue would be trying to solve for n, since the TVM formula uses USPV(i%:n) and SPPV(i%:n) internally. I'm thinking it's probably more trouble than it's worth to make this work on a 27S, and I'm better off sticking to true programmable financial calculators - like my DM42 or Casio fc-200 - for this kind of interest savings problem.