9.2 Compounding to Determine Future Values
223
Spreadsheet Solution:
We set up our spreadsheet with descriptive labels in cells A1 through A4. We then solve
the compound interest problem by placing the interest rate in decimal form (0.08) in Cell B1.
The time periods are placed on Row 2, beginning with period 0 (the current period) in Cell B2
and so forth. The cash fl ow of 1000 (an investment) is listed in cell B3. In this simple problem,
we fi rst replicate the basic “by hand” calculations in spreadsheet
format and the future value
calculations beginning in C4 and continuing to D4.
In Cell C4, we place the formula = B3*(1 + B1), which refl ects compounding the $1,000
investment at 8 percent interest for one year. Cell D4 shows compounding of the investment
at 8 percent for a second year and can be calculated as C4*(1 + B1), so compounding at an
8 percent interest rate results in a future value of $1,166.40 after two years. Of course, we
could have made the FV calculation in one step as = B3*(1 + B1)^2,
which also produces
$1,166.40.
Excel
and other spreadsheet programs have built-in “fi nancial functions” so that spread-
sheet solutions do not have to be calculated the “long way.” The bottom portion of the spread-
sheet solution example illustrates the use of the fi nancial function for future value. Here we
enter the cash fl ow in time period zero as –1000 to refl ect an outfl ow and a present value.
Click
on the Excel fi nancial wizard (
fx
) icon, then Financial, then FV, and then press OK to bring up
the dialogue box where the FV components for the problem at hand are requested. The equation
is FV(Rate, Nper, Pmt, PV, Type). The Rate is 0.08; Nper is the number of time periods (2 in
the preceding example); Pmt is 0, since
there are no periodic payments; PV is –1000; and Type
is 0, refl ecting that payments occur at the end of the period. Thus, we would have FV(0.08,2,0,
–1000,0). Pressing OK results in a FV of $1,166.40, or $1,166 rounded. Of course, rather than
inserting numbers, one could insert specifi c cell references in the FV function.
If the investment had
been compounded for ten years, the FV function inputs would have
been FV(0.08,10,0,–1000,0). Pressing OK would result in an answer of $2,158.92, or $2.159
rounded.
In addition, tables have been prepared to simplify the calculation eff ort if fi nancial calcu-
lators or spreadsheet programs are not available. Equation 9.1 can be rewritten as,
FV
n
= PV(FVIF
r
,
n
) (9.2)
where the (1 +
r
)
n
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