XL: How to Create Functions to Calculate Light Years

• Microsoft Excel for Windows, versions 5.0, 5.0c
• Microsoft Excel for Windows NT, version 5.0
• Microsoft Excel for Windows 95, versions 7.0, 7.0a
• Microsoft Excel 97 for Windows
• Microsoft Excel for the Macintosh, versions 5.0, 5.0a
• Microsoft Excel 98 Macintosh Edition

SUMMARY

Microsoft Excel does not include a function that will convert miles into light years or light years to miles. However, you can use the following formulas for this calculation

   Miles to Light Years = M / 5,877,000,000,000

   Light Years to Miles = LY * 5,877,000,000,000

MORE INFORMATION

Suppose you want to calculate the number of miles between the earth and the closest star system, Alpha Centauri. Alpha Centauri is 4.3 light years away.

The following formula typed into a cell on a worksheet, using the information above, will return a grand total of 25,271,100,000,000 miles:

   =4.3*5,877,000,000,000

Creating a Function Macro

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   Function LightYearsToMiles(LY) As Double
       Dim Convert As Double
       Convert = 5877000000000
       'Defines variables
       LightYearsToMiles = LY * Convert 'Performs computation
   End Function

   Function MilesToLightYears(M) As Double
       Dim Convert As Double
       Convert = 5877000000000
       'Defines variables
       MilesToLightYears = M / Convert 'Performs calculation
   End Function

1. Type the following in a worksheet:

         A1: 4.3
         A2: =LightYearsToMiles(A1)
         A3: =MilesToLightYears(A2)
   

2. The total number of miles, located in cell A2, between Earth and Alpha Centauri is 25,271,100,000,000 miles. The number of light years, located in cell A3, is 4.3.

3. Format cell A2 with the following format code: ###,###,###,###,###. To do this, select the Format menu, and choose Cells, the Number tab and Custom.

REFERENCES

"Visual Basic User's Guide," version 5.0, Chapter 3, "Creating a User-Defined Function"