The Museum of HP Calculators The Museum of HP Calculators
This program is Copyright © 1976 by Hewlett-Packard and is used here by permission. This program was originally published in the HP-67 Business Decisions Pac.
This program is supplied without representation or warranty of any kind. Hewlett-Packard Company and The Museum of HP Calculators therefore assume no responsibility and shall have no liability, consequential or otherwise, of any kind arising from the use of this program material or any part thereof.
| Accumulated Interest/Remaining Balance | |||||
| Shift | →Sched | P? | |||
| Label | J,K | i | PMT | PV | →INT;RB |
| Key | A | B | C | D | E |
This program finds both the total interest paid over a specified number of payment periods and the remaining balance at the end of the last specified period, given the periodic interest rate, periodic payment amount, loan amount, and the beginning and ending payment numbers for the time span being considered. The payments associated with both the beginning (J) and the ending (K) payment period are included in the calculation.
The program can be used for loans with a balloon payment as well as loans arranged to be fully amortized provided two cautions are observed. First, the balloon payment of the loan must be at the same time as, and in addition to the last payment. Second, care should be taken not to enter a value for K that is after the last payment since the program has no way of knowing the term of the loan.
An option is available to output the amortization schedule between payments J and K (f A).
Pressing f E sets and clears the print flag. Successive use of f E will alternately display 1.00 and 0.00, indicating that the print/pause mode is on or off respectively.
The data generated is valid for loans that have a balloon payment, as well as those that are arranged to be fully amortized. For loans with a balloon payment, the remaining balance of the last payment period is the balloon payment due in addition to the last periodic payment.
For loans scheduled to be fully amortized, the remaining balance after the last payment period may be slightly more or less than zero. This is because the program assumes that all payments are equal to the value entered for PMT. In fact for most loans, the last payment is slightly more or less than the rest.
The calculator performs all internal calculations to ten digits. If the user wishes to round the schedule to dollars and cents, the following sequence may be used:
| Step | Instructions | Input Data/Units | Keys | Output Data/Units |
| 1 | Load side 1 and side 2. | |||
| 2 | Optional: Select print/pause mode for amortization schedule. | f E | 1.00 or 0.00 | |
| 3 | Key in | |||
| Starting period number | J | A | J | |
| Ending period number | K | A | K | |
| Periodic interest rate | i (%) | B | i (%) | |
| Periodic payment amount | PMT | C | PMT | |
| Initial loan amount | PV | D | PV | |
| 4 | Compute the total interest paid between periods J and K inclusive, and the remaining balance at the end of period K. | E | INT | |
| R/S | BAL | |||
| OR | ||||
| 5 | Generate the amortization schedule between payments J and K inclusive. If the print/pause mode is on (1.00), the results are printed automatically. | f A | J | |
| 6 | Calculate amount paid to interest for period J. | R/S | PMT to INT | |
| 7 | Calculate amount paid to principal for period J. | R/S | PMT to PRIN | |
| 8 | Calculate remaining balance at the end of period J. | R/S | BAL | |
| 9 | Calculate total interest paid between periods J thru K inclusive. | R/S | TOT INT | |
| 10 | Increment J for next period. | R/S | J+1 | |
| If J ≤ K, go to step 6 for next period's values. Otherwise, stop. | ||||
| 11 | For a new case, go to step 2 and change appropriate input values. |
A mortgage is arranged such that the first payment is made at the end of October, 1975 (i.e., October is payment period 1). It is a $20,000 loan at 9%, with monthly payments of $167.84. What is the accumulated interest for 1975 (periods 1-3) and 1976 (periods 4-15) and what would the remaining balance be at the end of each year?
Keystrokes Outputs
1 A 3 A 9 ENTER↑ 12 ÷ B
167.84 C 20000 D E 449.60 (interest paid
in 1975)
R/S 19946.08 (remaining balance at
the end of 1975)
4 A 15 A E 1785.89 (interest paid
in 1976)
R/S 19717.88 (remaining balance at
the end of 1976)
Generate an amortization schedule for the first two payments of a $30,000, 7% mortgage having monthly payments of $200. Then jump ahead and generate the data for the 36th payment.
Keystrokes Outputs
1 A 2 A 7 ENTER↑ 12 ÷ B
200 C 30000 D f A 1.00 (starting 1st period)
R/S 175.00 (payment to interest)
R/S 25.00 (payment to principal)
R/S 29975.00 (remaining balance)
R/S 175.00 (total interest to
date)
R/S 2.00 (starting 2nd period)
R/S 174.85 (payment to interest)
R/S 25.15 (payment to principal)
R/S 29949.85 (remaining balance)
R/S 349.85 (total interest to date)
Now let's skip ahead to the 36th payment period.
36 A A f A 36.00 (starting 36th period) R/S 169.36 (payment to interest) R/S 30.64 (payment to principal) R/S 29001.75 (remaining balance) R/S 6201.75 (total interest to date)
LINE KEYS 001 *LBL A 002 RCL 0 003 STO 7 J→R7 004 X⇔Y K→R0 005 STO 0 006 RTN 007 *LBL B 008 EEX 009 2 i/100→R1 010 ÷ 011 STO 1 012 LST X 013 x 014 RTN 015 *LBL C 016 STO 2 PMT→R2 017 RTN 018 *LBL D 019 STO 3 020 RTN PV→R3 021 *LBL E 022 RCL 0 023 RCL 7 024 X≤Y? 025 GTO 0 026 STO 0 027 R↓ 028 STO 7 029 *LBL 0 030 1 031 RCL 1 032 + (1+i/100)→R8 033 STO 8 034 RCL 0 035 GSB 1 BALk→R4 036 STO 4 037 RCL 8 038 RCL 7 039 1 040 - 041 GSB 1 -BALj-1 042 CHS 043 RCL 4 044 + BALk - BALj-1→R6 045 STO 6 046 RCL 0 047 RCL 7 048 - 049 1 050 + 051 RCL 2 052 x 053 + 054 RTN INTj-k 055 RCL 4 BALk 056 R/S 057 *LBL a 058 RCL 7 059 F0? 060 PRT SPC 061 GSB 9 J 062 1 063 RCL 1 064 + 065 STO 8 066 RCL 7 067 GSB 1 068 STO 4 069 RCL 8 070 RCL 7 071 1 072 - 073 GSB 1 074 RCL 4 075 - 076 STO 6 077 RCL 2 078 X⇔Y 079 - INTj 080 GSB 9 081 RCL 6 082 GSB 9 PRINCj 083 RCL 4 084 GSB 9 RBALj 085 RCL 7 086 RCL 2 087 x 088 RCL 3 089 RCL 4 090 - 091 - 092 GSB 9 TOT INT 093 1 094 STO + 7 095 RCL 0 096 RCL 7 097 X≤Y? J≤K? 098 GTO a 099 RTN 100 *LBL 1 101 CHS 102 YX 103 STO 5 104 1 105 - 106 RCL 1 107 ÷ 108 RCL 2 109 x 110 RCL 3 111 + 112 RCL 5 113 ÷ RND may be inserted here. 114 RTN 115 *LBL e 116 F0? 117 GTO 2 Print mode option. 118 SF 0 119 1 120 RTN 121 *LBL 2 122 0 123 CF 0 124 RTN 125 *LBL 9 126 F0? 127 GTO 3 128 R/S 129 RTN 130 *LBL 3 131 PRTX 132 RTN 133 R/S
R0 K R1 i/100 R2 PMT R3 PV R4 Used R5 Used R6 Used R7 J R8 1+i/100
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