o=o=o=o=o=› ›     COMPOUND INTEREST FOR BCALC› ›          By Frank Walters› ›   INTEREST.BC is a template file for› BCALC  spreadsheet.  BCALC, by Barry› Kolbe   and   Bryan   Schappel,  was› published  in ANALOG magazine, issue› 63, August 1988.› › PURPOSE OF INTEREST.BC:› ›   Used  to  compute monthly interest› and  balances  for  any bank account› using   fixed  interest,  compounded› monthly.  It  is  not  suitable  for› variable  interest  rate investments› as   the  rates  are  unpredictable.› INTEREST.BC  covers a five year span› and  requires  only  a  few,  simple› entries  to  produce  a  printout of› your  future  investment  prospects,› month by month.› ›   Note that it uses all 64 available› lines in BCALC, so more than 5 years› is  not  practical  at one time. For› longer terms you could print 4 years› at a time, load a fresh template and› update  the years and leap year days› and  use  the  ending balance of the› 4th  year as the starting balance of› the 5th year.› › SETUP:› ›   Load   BCALC.COM  into  any  Atari› 8-bit  computer with BASIC disabled.› Minimum of 48k required. From BCALC,› press any key and then SELECT, which› allows   commands   from   the  text› window.  Type LOAD D:INTEREST.BC and› press  Return  to load the file from› drive 1.› ›   AA01  shows  the  filename  of the› template.    AA02,AB02   display   a› wraparound of the Balance that would› appear  on JAN, following AA64-AB64,› completing a full 5 year cycle.› ›   AA05-AA64  label  60  months  in 5› years.   AB05-AB64   show   computed› balances  for  each month. Column AC› has interest earned during the month› labeled  on the same line. AD is the› number  of days per month. AE is the› result  of  a  formula that computes› interest  rate for that month, based› on number of days and annual rate in› AC04.› ›   =(AC04/100/365)*ADxx)› ›   AC04/100  converts  annual percent› to  decimal, which is divided by 365› days   to   convert  it  to  1-day's› interest. *ADxx multiplies number of› days  in  row xx to compute interest› rate  for the specific month on that› row. It is unnecessary to print rows› AE and AF, which is on-screen help.› › ENTERING YOUR DATA:› ›   Refer to your bank statement or CD› certificate    to    determine   the› starting  date, Principal and actual› interest  rate.  DO  NOT  USE ANNUAL› PERCENTAGE YIELD (APY) RATE.› ›   Cell  AC04 is where you enter your› interest  rate. Then scan cells AA05› thru AA16 to find the starting month› of  your investment. Edit AA cell to› add  day,  year  to that month. Move› right  to  AB  cell of same line and› type amount of Principal in the 0.00› cell,  replacing  a  formula in that› cell:› ›       AA            AB› › 09>MAY 1, 1997   5,200.75› ›   DO  NOT USE COMMA during entry, it› will  be  added automatically by the› program.   Because  you  replaced  a› formula  in  column  AB,  you cannot› re-use  this  same template for more› than  one  account.  After printing,› you  must  re-load  INTEREST.BC from› disk  to  enter  a new Principal and› interest rate.› ›   Move  cursor  down column AA until› you reach the year and month of your› maturity  date.  Edit  date,  adding› day,  year  of  your  maturity date.› This   will  mark  your  Balance  at› maturity  in  column  AB. That's all› your   entries:  two  text  and  two› numeric entires and you are ready to› calculate and print.› › RECALCULATE--CONTROL-A:› ›   You must now recalculate a minimum› of   three   times   to  insure  all› formulas  are  correctly  applied in› the proper sequence. Use CTRL-A each› time.   Screen   will   flicker  and› re-draw  as  each  recalculation  is› completed.  Your  cursor will return› to cell AA01.› ›   Move   cursor   down  to  date  of› maturity   and  you  will  see  your› balance  at  that  date.  Each  line› shows   the   balance  and  interest› earned during that month, which will› be  added  to the balance to compute› the next month's balance.› ›   All balances and interest prior to› your  starting month should be 0.00.› Balances  below  your  maturity date› are  projected amounts, based on the› same interest rates.› › PRINTING YOUR RESULT:› ›   The entire spreadsheet will fit on› one  80 column printer page but that› is unnecessary. To selectively print› the  entire term of your investment,› place  cursor  on cell AAnn (nn=line› number of date of Principal.)› ›    Home  cursor  to  AA01  and Press› CTRL-P.  Press Return to mark upper/› left  of  block  of  cells to print.› Cursor  down  to  line  number  (xx)› containing  your  maturity  date and› cursor  right  to  cell ADxx on that› line   and   press  Return.  Printer› should  be  turned  on  and ready to› print. That's all there is to it.› › CHANGING YEAR DATES IN 1998:› ›   Once   you   print  each  of  your› savings,  checking,  or CD accounts,› there   is   no  need  to  use  this› template  for  them again unless you› lose  the  printout.  But for future› deposits  you may have to update the› years  in column AA at the beginning› of 1998, 1999, etc.› ›   Simply  edit  each cell in AA that› contains  a  year and change them to› the next higher year. Year 2000 is a› leap  year  with  29 days in FEB. Be› sure  to  change the 28 to 29 in FEB› of  the  new  year  2000,  and  also› change  the  29  to 28 in FEB of the› new  year  2001.  The  days  are  in› column  AD,  across from the name of› the  appropriate month. Then re-save› the  updated  template  to  disk. Be› sure  you edit the original template› and not one you have already entered› dollars  and  interest  rate.  After› saving  the zeroed template then you› can  enter  new balance and interest› rate, etc.› › BANK INTEREST DOES NOT AGREE:› ›   A  very  few  banks  use a dubious› practice  of  not paying interest on› day   of  deposit  but  instead  pay› interest  on  day  of maturity. That› results   in   the   first   month's› interest  being  1 day less than the› number   of   days  in  that  month.› Subsequent   months   will   compute› interest based on the correct number› of  days  but  your  balance  on the› second  month  would  start  out too› small.  To  adjust  for  this sneaky› practice you can subtract 1 day from› the days of the month you opened the› account  in cell AD and add 1 day to› cell  AD  in the month PRIOR to your› month  of  maturity.  This  interest› will  be  added to the prior month's› balance   to   create  the  maturity› month's balance.› ›   OR--you could go down to your bank› and complain to the manager that you› are  being  cheated out of one day's› interest,  compounded  over the term› of  your  account. That's what