SUM function
This article describes the formula syntax and usage of the SUMfunction in Microsoft Office Excel.
Description
The SUM function adds all the numbers that you specify as arguments. Each argument can be a range, a cell reference, an array, a constant, a formula, or the result from another function. For example, SUM(A1:A5) adds all the numbers that are contained in cells A1 through A5. For another example, SUM(A1, A3, A5) adds the numbers that are contained in cells A1, A3, and A5.
Syntax
SUM(number1, [number2], [number3], [number4], ...)
The SUM function syntax has the following arguments:

number1 Required. The first item that you want to add.

number2, number3, number4, ... Optional. The remaining items that you want to add, up to a total of 255 items.
Example
The example may be easier to understand if you copy it to a blank worksheet.
How do I copy an example?

Select the example in this article.
Important Do not select the row or column headers.
Selecting an example from Help

Press CTRL+C.

In Excel, create a blank workbook or worksheet.

In the worksheet, select cell A1, and press CTRL+V.
Important For the example to work properly, you must paste it into cell A1 of the worksheet.

To switch between viewing the results and viewing the formulas that return the results, press CTRL+` (grave accent), or on the Formulas tab, in the Formula Auditing group, click the Show Formulas button.
After you copy the example to a blank worksheet, you can adapt it to suit your needs.


Remarks

If an argument is an array or reference, only numbers in that array or reference are counted. Empty cells, logical values, or text in the array or reference are ignored.

If any arguments are error values, or if any arguments are text that cannot be translated into numbers, Excel displays an error.