Microsoft KB Archive/191017

= XL98: How to Calculate Compound Interest =

Article ID: 191017

Article Last Modified on 6/17/2005

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APPLIES TO


 * Microsoft Excel 98 for Macintosh

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This article was previously published under Q191017



For a Microsoft Excel for Windows version of this article, see 141695.



SUMMARY
Compound interest is the amount that a dollar invested now will be worth in a given number of periods at a given compounded interest rate per period. Although Microsoft Excel 98 Macintosh Edition does not include a function for determining compound interest, you can use the following formula for this calculation:

=PV*(1+R)^N

where PV is present value, R is the interest rate, and N is the number of investment periods.



MORE INFORMATION
Suppose you have $1,000.00 in an investment account. The account pays 8 percent interest and this interest is compounded annually. How much will the investment be worth at the end of three years? There are two ways to find the amount:
 * Use a Fixed Formula
 * Create a Function Macro to Determine Compound Interest

Use a Fixed Formula
The following formula typed into a cell on a worksheet, returns the correct value of $1,259.71:

=1000*(1+.08)^3

However, all of the information is 'hard-coded' into the formula and you must manually change the formula any time the figures change.

Create a Function Macro to Determine Compound Interest
Microsoft provides programming examples for illustration only, without warranty either expressed or implied. This includes, but is not limited to, the implied warranties of merchantability or fitness for a particular purpose. This article assumes that you are familiar with the programming language that is being demonstrated and with the tools that are used to create and to debug procedures. Microsoft support engineers can help explain the functionality of a particular procedure, but they will not modify these examples to provide added functionality or construct procedures to meet your specific requirements.

A custom function is more flexible because none of the actual raw data is 'hard-coded' into the function; the user just types the data for the calculation instead of the actual calculation. To create this custom function, type the following code in a new Visual Basic module: Function Yearly_Rate(PV, R, N) As Double

Yearly_Rate = PV*(1+R)^N   'Performs computation

End Function To use the custom function, follow these steps:   Type the following values in your worksheet:   A1:  1000 A2:  .08 A3:    3 These values represent the following:

 A1: Present value of the investment A2: Interest rate A3: Number of investment periods  In any blank cell, type the following formula

=Yearly_Rate(A1,A2,A3)

where A1, A2, and A3 are the cells that contain the present value, interest rate, and number of investment periods respectively.</li></ol>

The cell in which you typed the formula displays $1,259.71. This is the amount your original investment of $1000.00 is worth after three investment periods at 8 percent compound interest.

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