Sometimes, as you’re working in an Excel 2013 spreadhseet, it’s awkward or lengthy to write a formula to perform a calculation. For example, suppose you want to sum the values in cells A1 through A10. To express that as a formula, you’d have to write each cell reference individually, like this:

`=A1+A2+A3+A4+A5+A6+A7+A8+A9+A10`

## All about functions in Excel

In Excel, a function refers to a certain math calculation. Functions can greatly reduce the amount of typing you have to do to create a particular result. For example, instead of using the =A1+A2+A3+A4+A5+A6+A7+A8+A9+A10 formula, you could use the SUM function like this: =SUM(A1:A10).

With a function, you can represent a range with the upper-left corner’s cell reference, a colon, and the lower-right corner’s cell reference. In the case of A1:A10, there is only one column, so the upper-left corner is cell A1, and the lower-right corner is cell A10.

Range references cannot be used in simple formulas — only in functions. For example, =A6:A9 would be invalid as a formula because no math operation is specified in it. You can’t insert math operators within a range. To use ranges in a calculation, you must use a function.

An argument in Excel is a placeholder for a number, text string, or cell reference. For example, the SUM function requires at least one argument: a range of cells. So, in the preceding example, A1:A10 is the argument. The arguments for a function are enclosed in a set of parentheses.

Each function has one or more arguments, along with its own rules about how many required and optional arguments there are and what they represent. You don’t have to memorize the sequence of arguments (the syntax) for each function; Excel asks you for them. Excel can even suggest a function to use for a certain situation if you aren’t sure what you need.

The syntax is the sequence of arguments for a function. When there are multiple arguments in the syntax, they are separated by commas.

## Using the SUM function

The SUM function is by far the most popular function; it sums (that is, adds) a data range consisting of one or more cells, like this:

`=SUM(D12:D15)`

You don’t have to use a range in a SUM function; you can specify the individual cell addresses if you want. Separate them by commas, like this:

`=SUM(D12, D13, D14, D15)`

If the data range is not a contiguous block, you need to specify the individual cells that are outside the block. The main block is one argument, and each individual other cell is an additional argument, like this:

`=SUM(D12:D15, E22)`