My HP 10bII+ is much faster than HP 12c!

[Albert Chan]

(01-06-2020 11:07 PM)lrdheat Wrote:  On the Prime G2, if I uncheck “End” and make N=29, FV=49,000, P/Yr=1: I get I=3.64 Is this coincidental?

With End Off, it is identical to End On, but with payments shifted up:

PV ← PV + PMT
FV ← FV − PMT

Above is plain savings plan (with "End" On): N=29, PV=0, PMT=-1000, FV=50000 → I=3.639%

You can visualize it as original N=30 example, PV=1000 getting no interest, and got cancelled by first PMT.
The error is tiny, but to correct for this, we can iterate again.

PV gives up 1000 * 3.639% = 36.39
FV correction = 36.39 * 1.03639²⁹ = 102.60

Rerun solver, with N=29, PV=0, PMT=-1000, FV=50102.60 → I=3.652%