HP Prime: Length of a Loan with a Certain Payment
Introduction
The program PMTLENGTH will calculate how many payments that
are required to finish a loan, given a certain annual interest rate and
payment. Payments are assumed to be
monthly, and end of period. The program
will also return the last payment. Due
to the rounding in the financial algorithms, the last payment is an approximate
(unless the interest rate is 0%).
Input:
PMTLENGTH(I,P,X)
I = annual interest rate
P = loan amount
X = payment amount, enter as a negative amount
Firmware 13441 or later is required.
HP Prime Program PMTLENGTH
EXPORT
PMTLENGTH(I,P,X)
BEGIN
// I%YR, PV, PMT (as negative)
// 2018-03-19 EWS
// how many monthly payments?
// last payment? (FV)
LOCAL N,B;
N:=Finance.TvmNbPmt(I,P,X,0,12);
B:=P;
IF FP(N)≠0 THEN
B:=Finance.TvmFV(IP(N),I,P,X,12);
N:=IP(N)+1;
END;
// {N, final pmt}
RETURN {N,B};
END;
Examples
Example 1: How long
will I take to pay off a $2,000 loan if I make $600 payments each month? This is a no interest loan.
Result: {4, -200}
It will take 4 payments, with the last payment being $200.
Example 2: How long
will I take to pay off a $5,350 loan if I make $750 monthly payments each
month? The loan has a 10% monthly
interest rate.
Result: {8,
-286.906502677}
It will take 8 payments, with the last payment being about
$286.91.
Eddie
This blog is property of Edward Shore, 2018.
