Compound Interest & Investing

Not being a financial guru I can not vouch for the accuracy of this information but you can use it as a guideline when making inquiries. Some of the banking personnel that I questioned could not give me further information since as one said “I just punch the numbers in and the computer does the work, I have no idea of how the program is set up”.

The program is useful for figuring comparison data to make that decision if this interest rate compounded at this frequency is better than another rate with different rates and frequencies. This program will work with series EE Savings Bonds only if they are cashed after being held for more than five years. For the bonds with a cash in date of six months to less than five years the rate begins at 4.16% and seems to increase at the rate of .184% for each elapsed six month period to reach the minimum guaranteed rate of 6%. Bonds purchased after October 1992 may have a lower guaranteed rate.

I have set the program with lines to SAVE for cassette, LarKen and Oliger disk interfaces. You will note that the program halts upon LOADing and to get it to autorun remove the STOP command from LINE 7. In the event that you wish to enter the LISTing while running the program enter letters at the PRINCIPAL prompt. This program was extracted from a more complete financial program in the SNUG Oliger disk library.

Originally I wanted to know how long it takes to double money at various interest rates and different compounding times. You will note that in the program it asks for how many times and that refers to how many compounding are to be used. For instance with daily compounding entering 365 will mean a year, with quarterly enter 4 for a year. If you have a different time between compounding then the way to get it is in lines 330 to 336. Using those lines as a cue it is easy to do, if a non programmer like me can do it you can, I added the semi-annual to try to track the growth of series EE Savings Bonds.

If the TS2040 printer is turned on it will print it all out as you go along. The program is not neat and elegant but it works. And it is not long to type in.

  10 REM "B-9" from Carl Terry
         SINCUS, 1984
  20 FOR F=26714 TO 26714+PEEK 2
6712
  30 IF PEEK F=94 THEN POKE F,6
  40 NEXT F
  50 POKE 23652,10
  60 CLEAR
  70 BORDER 0
  80 PAPER 0
  90 INK 7
 100 CLS : REM COMPOUND INTEREST
 110 PRINT TAB 7;"COMPOUND INTER
EST"''
 120 LPRINT TAB 7;"COMPOUND INTE
REST"''
 130 PRINT "ENTER PRINCIPLE?"
 140 LPRINT "ENTER PRINCIPLE?"
 150 INPUT A
 160 PRINT "$";A''
 170 LPRINT "$";A''
 180 PRINT "ENTER INTEREST(in de
cimal form)"
 190 LPRINT "ENTER INTEREST(in d
ecimal form)"
 200 INPUT B
 210 PRINT B*100;"%"''
 220 LPRINT B*100;"%"''
 230 PRINT "COMPOUND PERIOD"',"-
1-YEARLY"',"-2-MONTHLEY"',"-3-QU
ARTERLY"',"-4-DAILY"',"-5-SEMI-A
NNUALLY"
 240 LPRINT "COMPOUND PERIOD"',"
-1-YEARLY"',"-2-MONTHLEY"',"-3-Q
UARTERLY"',"-4-DAILY"',"-5-SEMI-
ANNUALLY"
 250 INPUT C
 260 PRINT C'
 270 LPRINT C'
 280 IF C=1 THEN LET D=B
 290 IF C=2 THEN LET D=B/12
 300 IF C=3 THEN LET D=B/4
 310 IF C=4 THEN LET D=B/365
 320 IF C=5 THEN LET D=B/2
 330 PRINT "NUMBER OF TIMES IN A
BOVE UNITS ?"
 340 LPRINT "NUMBER OF TIMES IN
ABOVE UNITS ?"
 350 INPUT F
 360 PRINT F''
 370 LPRINT F''
 380 LET G=A*(1+D)^F
 390 LET H=G-A
 400 PRINT "NEW BALANCE","INTERE
ST EARNED"'
 410 LPRINT "NEW BALANCE","INTER
EST EARNED"'
 420 PRINT FLASH 1;"$";INT (100*
G+.5)/100,"$";INT (100*H+.5)/100
 430 LPRINT ;"$";INT (100*G+.5)/
100,"$";INT (100*H+.5)/100
 440 INPUT "PRESS ENTER FOR MENU
";Z$
 450 GO TO 100
 460 CLEAR : SAVE /"compound" LI
NE 1: BEEP .01,.77
9992 CLEAR : RANDOMIZE USR 100:
SAVE "compnd.B1" LINE 10: BEEP .
01,.77
9998 RANDOMIZE USR 100: LOAD "L.
B1"