About functions

Functions are predefined formulas that perform calculations by using specific values, called arguments, in a particular order, or structure. Functions can be used to perform simple or complex calculations. For example, the ROUND function rounds off a number in cell A10.

Structure of a function

Structure. The structure of a function begins with an equal sign (=), followed by the function name, an opening parenthesis, the arguments for the function separated by commas, and a closing parenthesis.

Function name. For a list of available functions, click a cell and press SHIFT+F3.

Arguments. Arguments can be numbers, text, logical values such as TRUE or FALSE, arrays, error values such as #N/A, or cell references. The argument you designate must produce a valid value for that argument. Arguments can also be constants, formulas, or other functions.

Argument tooltip. A tooltip with the syntax and arguments appears as you type the function. For example, type =ROUND( and the tooltip appears. Tooltips only appear for built-in functions.

Entering formulas When you create a formula that contains a function, the Insert Function dialog box helps you enter worksheet functions. As you enter a function into the formula, the Insert Function dialog box displays the name of the function, each of its arguments, a description of the function and each argument, the current result of the function, and the current result of the entire formula.

Nested functions

In certain cases, you may need to use a function as one of the arguments of another function. For example, the following formula uses a nested AVERAGE function and compares the result with the value 50.

Nested functions

Valid returns When a nested function is used as an argument, it must return the same type of value that the argument uses. For example, if the argument returns a TRUE or FALSE value, then the nested function must return a TRUE or FALSE. If it doesn't, Microsoft Excel displays a #VALUE! error value.

Nesting level limits A formula can contain up to seven levels of nested functions. When Function B is used as an argument in Function A, Function B is a second-level function. For instance, the AVERAGE function and the SUM function are both second-level functions because they are arguments of the IF function. A function nested within the AVERAGE function would be a third-level function, and so on.