Section 4: Programming 267
Label B: Given $2000 initially plus $185 per month invested at 1% per month. What is the monthly total savings? This also is a compound growth schedule with a growth (interest) factor of 1.01 but with an addition of $185 monthly to the amount being compounded.
Label C: This is simply the difference between required downpayment and savings (label A minus label B).
Label D: What is the number of months required for the savings to overtake the required downpayment?
Label E: What is the difference between savings and required downpayment at a specified month—say 8 months hence?
Figure 4-6 shows the monthly answers for labels A, B, and C for the first 12 months.
Month Label A
Required
Downpayment
(4000) 		Label B  
Savings
(2000) 		Label C
Difference
  1  
  2  
  3  
  4  
  5  
  6  
  7  
  8  
  9  
  10  
  11  
  12  
  4020.00  
  4040.10  
  4060.30  
  4080.60  
  4101.01  
  4121.51  
  4142.12  
  4162.83  
  4183.64  
  4204.56  
  4225.58  
  4246.71  
  2205.00  
  2412.05  
  2621.17  
  2832.38  
  3045.71  
  3261.16  
  3478.77  
  3698.56  
  3920.55  
  4144.75  
  4371.20  
  4599.91  
– 1815.00  
– 1628.05  
– 1439.13  
– 1248.22  
– 1055.30  
– 860.35  
– 663.34  
– 464.27  
– 263.09  
– 59.81  
  145.52  
  353.20  
   Note that the calculation assumes the monthly amount to be deposited at the end of the month; this is an ordinary annuity in business parlance. The Personal Investment Program in the Standard Pac, on the other hand, assumes the monthly amount to be deposited at the beginning of the month; this is an annuity due in business parlance.
Figure 4-6. Calculation Results