The Excel OR function tests a number of supplied conditions and returns either:
  TRUE if ANY of the conditions evaluate to TRUE 
or  
  FALSE otherwise (i.e. if ALL of the conditions evaluate to FALSE) 
The syntax of the function is :
where the logical_test arguments are one or more conditions that evaluate to either TRUE or FALSE.
You can enter up to 255 conditions to the Excel Or function in Excel 2007 or 2010. However, in Excel 2003, the function can only handle up to 30 arguments.
Note that, if the logical_tests return numbers, instead of logical values, zero is treated as the logical value FALSE all nonzero numbers are treated as the logical value TRUE.
The following spreadsheet shows three examples of the Excel Or function.
The spreadsheet on the left shows the formulas and the spreadsheet on the right shows the results.
Formulas:

Results:

Note that, in the above examples:
More examples of the Excel Or function are provided on the Microsoft Office website.
The most common error from the Excel Or Function is the #VALUE! error:
#VALUE!    Occurs if any of the supplied logical_test arguments are text values 