Calc includes over 350 functions to help you analyze and reference data. Many of these functions are for use with numbers, but many others are used with dates and times, or even text. A function may be as simple as adding two numbers together, or finding the average of a list of numbers. Alternatively, it may be as complex as calculating the standard deviation of a sample, or a hyperbolic tangent of a number. See a list of all functions in functions listed by category.

Typically, the name of a function is an abbreviated description of what the function does. For instance, the FV function gives the future value of an investment, while BIN2HEX converts a binary number to a hexadecimal number. By tradition, functions are entered entirely in upper case letters, although Calc will read them correctly if they are in lower or mixed case, too.

A few basic functions are also represented by symbols. For instance, SUM, which adds arguments, can also be entered as + while PRODUCT, which multiplies arguments, can also be entered as *.

Each function has a number of arguments used in the calculations. These arguments may or may not have their own name. Your job is to enter the arguments needed to run the function. In some cases, the arguments have pre-defined choices, and you may need to refer to the online help or Appendix B (Description of Functions) in this book to understand them. More often, however, an argument is a value that you enter manually, or one already entered in a cell or range of cells on the spreadsheet. In Calc, you can enter values from other cells by typing in their name or range, or—unlike the case in some spreadsheets—by selecting cells with the mouse. Should the values in the cells change, then the result of the function is automatically updated.

Strictly speaking, when all the arguments are entered and a function is ready to run, it becomes a formula. These terms are sometimes used interchangeably, but the distinction is worth preserving, because a formula can use functions as an argument.

For compatibility, functions and their arguments in Calc have almost identical names to their counterparts in Microsoft Excel. However, both Excel and Calc have functions that the other lacks. Occasionally, too, functions with the same names in Calc and Excel have different arguments, or slightly different names for the same argument—neither of which can be imported to the other. However, perhaps nine-tenths of functions can be imported between Calc and Excel without any problems.