SUM function
Adds all the numbers in the specified arguments.
Syntax
SUM(number1,number2,...)
Number1, number2,... are 1 to 30 arguments for which you want the total value or sum.
Remarks

Numbers, logical values, and text representations of numbers that you type directly into the list of arguments are counted. See the first and second examples following.

Arguments cause errors if they are error values or text that cannot be translated into numbers.
Examples
Col1 
Col2 
Col3 
Col4 
Col5 
Formula 
Description (Result) 
5 
15 
30 
TRUE 
=SUM(3, 2) 
Adds 3 and 2 (5) 

5 
15 
30 
TRUE 
=SUM("5", 15, TRUE) 
Adds 5, 15 and 1, because the text values are translated into numbers, and the logical value TRUE is translated into the number 1 (21) 

5 
15 
30 
TRUE 
=SUM([Col1], [Col2], [Col3]) 
Adds the first three numbers in the columns (40) 

5 
15 
30 
TRUE 
=SUM([Col1], [Col2], [Col3], 15) 
Adds the first three numbers in the columns, and 15 (55) 

5 
15 
30 
TRUE 
=SUM([Col4], [Col5], 2) 
Adds the values in the last two columns and 2 (3) 