Related Functions:
 AVERAGE function
 PRODUCT function
 SUMIF function
The SUM function adds together a supplied set of numbers and returns the sum of these values.
Syntax
=SUM(num_1,[num_2], … )
Note: Beginning with Excel 2007, you can enter up to 255 number arguments to the function. Excel 2003 would only accept up to 30 number arguments. However, each argument can consist of an array of values or a range of cells, each of which can contain many values.
Arguments
Argument  Description  

num_1, [num_2], … 
The arguments, num_1, [num_2], etc, are a set of numbers, or arrays of numbers, that you want to find the sum of

Values Counted as Numeric
Numbers and dates are always counted as numeric values by the SUM function. However, text representations and logical values are handled differently, depending on whether they are values stored in the cells of your spreadsheet, or they are supplied directly to the function.
Value Within a Range of Cells  Value Supplied Directly to Function  

Numbers  Included  Included  
Dates  Included  Included  
Logical Values  Ignored  Included (True1; False=0) 

Text Representations of Numbers & Dates  Ignored  Included  
Other Text  Ignored  #VALUE! Error  
Errors  Error  Error 
Examples
A  B  C  D  

1  Data  
2  5  =SUM(A2:A6)  35  
3  10  =SUM(5+6,7,8,9)  35  
4  15  =SUM(A2:A4,8,0)  35  
5  20  =SUM(A2,A3,A4,”8″,”9″)  35  
6  ’10  =SUM({5,6,7},8,9)  35  
7  TRUE  
8  
9  Formula  Result  Notes  
10  =SUM(A2,A3)  5  Adds the value in A2 and A3  
11  =SUM(A2:A4,15)  20  Adds the values in A2 through A4, and then adds 15  
12  =SUM(“5”,15,TRUE)  21  Adds 5, 15 and 1. The text value “5” is translated into a number and the logical value TRUE is translated into the number 1  
13  =SUM(A3,A5,A6,A7)  30  Adds the values in A3 and A5 through A7. Because nonnumeric values in references aren’t translated; the value in cell A6 (’10) and the value in cell A7 (TRUE) are both treated as text 
Common Function Error(s)
Problem  What went wrong 

Some numbers aren’t added  If an argument is a cell range or reference, only numeric values in the reference or range can be added. Empty cells, logical values like TRUE, or text are ignored 
#NAME? error  This usually means that the formula is misspelled 