One of the most popular functions available in Excel is the AutoSum function. Excel AutoSum automatically totals the contents of cells.

Excel AutoSum is a formula that calculates (by default) the total from the adjacent cell up to the first non-numeric cell using the SUM() function in its formula. The AutoSum feature provides a quick way to sum a contiguous range of numbers (that means there are no empty cells in a range). The range may be a single cell or thousands of cells.

The AutoSum icon is the Greek capital letter Sigma ∑. Math and Science use the Sigma ∑ as a summation operator. 

01. HOW TO USE SUM FUNCTION IN EXCEL?

The SUM function is a mathematical function in Excel that totals values in one or more cells in a range and displays the result in the cell containing the function. It is applicable for both contiguous and non-contiguous cells or ranges.

In the case of contiguous cells or ranges, select them by the dragging of the mouse or by the Shift and navigation arrows.

For non-contiguous cells or ranges, hold the CTRL-key and select them by dragging the mouse.

The syntax for the SUM function:number1, number2,… The values we want to add

Note: Brackets [ ] indicate optional arguments; however, do not actually type the brackets when we enter the argument.

The SUM function contains one required argument (number1) that represents a range of cells to add. For example, =SUM(B3:D3). Excel will sum all cells within that range.

We can enter up to 255 arguments into the SUM() function. For example, the following formula returns the sum of the values in three separate ranges: =SUM(B3:D3,B7:D7,B10:D10).

We can apply the SUM Function in a cell with 03 different methods:

• Method 1: Apply SUM Function With ‘Formula AutoComplete Tool’

(01) Select the cell where to apply SUM function ➪ place equality sign (=) and type sum, Excel by default select the SUM function from the drop-down list; otherwise select the SUM function with down navigation arrow (⬇).

Note that the upper or lower case does not matter for syntax, Excel by default considers it in upper case.  

(02) Then press the Tab key which allows us to open the SUM function with an open parenthesis.

(03) Select the range.

(04) Then press Ctrl+Enter or Enter to accept the formula.

• Method 2: Apply SUM Function With ‘Insert Function’ dialog box

(01) Select the cell where to apply the SUM function.

(02) Press Shift+F3 which will open the ‘Insert Function’ dialog box. Excel automatically places an equal sign (=) in the cell.

➢ Type and Search SUM function in ‘Search for a function:’ box ➪ then click OK or,

➢ Click to choose a category from ‘Or select a category:’ drop-down list, for example, select ‘Math & Trig’ category and find the SUM function using the horizontal scroll bar ➪ then click OK.

Note: Excel’s built-in functions are grouped into ten categories. 

(03) As a result, the ‘Function Arguments’ dialog box appears. Depending on the individual function’s arguments, select the required cells for each argument expected by the function. We can select a cell or range of cells and Excel automatically adds the references to the argument. However, we can also type a range or cell address directly in the argument text box. 

Selects the range (i.e., B3:D3) in the Number1 box. If required, we can select multiple necessary cell references to complete all of the function’s arguments.

(04) When finished constructing the arguments, press Enter or click OK to accept the formula.

Note: Excel displays the function results in the cell and the function appears in the Formula bar. 

• Method 3: Apply SUM Function With ‘Insert Function’ button on the Formula Bar

(01) Select the cell where to apply the SUM function.

(02) Click the ‘Insert Function’ button (fx) on the formula bar which will open the ‘Insert Function’ dialog box. Excel automatically place an equal sign (=) in the cell.

Either type and search SUM function in the ‘Search for a function:’ box or click to choose a category from ‘Or select a category:’ drop-down list and select the SUM function ➪ then click OK.

➢ Alternatively, go to the ‘Formulas’ tab ➪ Click the ‘Insert Function’ button (fx) in the function library group.

(03) As a result, another ‘Function Arguments’ dialog box opens ➪ Select the range (i.e., B3:D3) in the Number1 box; similarly we can select multiple different ranges ➪ Press Enter or click OK to accept the formula.

• Method 4: Apply SUM Function With AutoSum Excel

When we apply AutoSum, Excel first checks is there any contiguous range of values above the current cell, if there are, Excel will sum the values above it; otherwise, it will check are there any values to the left of it and if there are it will sum those values. We can change the range if required.