SUM Function is a very popular and useful formula in Microsoft Excel. It is one of the most basic, widely used, and easy to understand arithmetic functions in Excel. As the name suggests SUM Function in Excel performs the addition of numbers. Sum Function can accept numbers both as individual arguments and also as a complete range of cells.

## How Excel Defines SUM Function

Microsoft Excel defines SUM as a formula that “Adds all the numbers in a range of cells”. This definition clearly points out that the Sum function has a job to add numbers and the arguments can be supplied using combinations of both numbers and the range of cells.

## Syntax of SUM Function in Excel

Sum function has two syntaxes and hence they can be written in two different ways:

`=SUM( num1, num2, ... num_n )`

Here 'num1', 'num2', and 'num_n' specifies numbers which you wish to add.

OR

`=SUM(CellRange1,CellRange2, ... CellRange_n)`

Here 'CellRange1', 'CellRange2', 'CellRange_n' specifies multiple cell ranges (containing numbers) which are to be added.

## Some Important Facts about SUM Formula

- Sum function can also do the addition of decimal numbers and fractions.
- If you are using the SUM formula as =SUM( num1, num2, … num_n ) and in place of ‘num’ you have entered a non-numeric content then the Sum function will throw an #Name? error.
- But if you are using SUM Function as =SUM ( CellRange1, CellRange2, … CellRange_n ) and if any of the cell range contains a non-numeric content then Sum function will ignore this value.
- Sum function is not a dynamic type of function. This means that if you have applied a Sum formula on a range of cells and then you filter out some values then the output of the Sum function won’t change as it doesn’t change its result according to the current values in the filter. It is better to use the Subtotal function in such cases.

## Examples of SUM Formula

In the above example, I have applied four types of SUM functions and below I will explain them one by one.

**Example 1.** In the first example, I have used the SUM function

`=SUM(10,11,19)`

This Sum function simply adds-up all the values i.e. 10, 11, and 19, and hence the result is 40.

**Example 2.** In the second example, I have used a function

`=SUM(10.2,9.6,2,4)`

Simple mathematics can tell us that 10.2+9.6+2.4 is 25.8 and hence the output is 25.8.

**Example 3.** In the third example, a fraction type Sum function is used as

`=SUM(4/2,8/2)`

As 4/2 results into 2 and 8/2 results into 4 and the addition of both these give the result 6.

**Example 4**. In the fourth example, the Sum function is used with a non-numeric value

`=SUM(10,EXCEL)`

And this is the reason why it results in a #Name? error.

**Example 5.** In the above image, I have used the second type of SUM function as

`=SUM(B2:B10)`

to which I have supplied a range of cells (B2:B10) as arguments. This sum function simply adds each element of the range and delivers the result as 60.

## Shortcut for Applying SUM Formula in Excel

Instead of applying the sum formula in the normal way, you can also apply the SUM Formula using a shortcut.

Simply select the range (containing your numbers to be added), then press “**Alt +**” key and the desired sum will be populated in the next cell.

## Using Mathematical Operators inside SUM Function

Mathematical operators like (+,-, / and *) can also be used inside Sum functions. This means that a SUM function as:

`=SUM(2*4)`

is valid and it will result in 8. Similarly, a SUM Function as follows

`=SUM(62-4)`

is also valid and it results in 58.

Actually, this happens because the Sum Function treats this whole set of numbers and operators as a single expression. So, first of all, it evaluates the result of this mathematical operation, and as there is no other argument supplied to the function so it shows the result as it is.