Understanding the structure of functions
Except for simple functions such as + or *, all functions have a similar structure. If you use the right tool for entering a function, you can escape learning this structure, but it is still worth knowing for troubleshooting.
To give a typical example, the structure of a function to find cells that match entered search criteria is:
= DCOUNT (Database;Database field;Search_criteria)
Like most functions, this one starts with an equal sign. It is followed by DCOUNT, the name of the function. After the name of the function comes its arguments. All arguments are required, unless specifically listed as optional.
Arguments are added within the brackets (parentheses) and separated by semicolons, with no space between the arguments and the semicolons. Many arguments are a number. A Calc function can take up to thirty numbers as an argument. That may not sound like much at first. However, when you realize that the number can be not only a number or a single cell, but also an array or range of cells that contain several or even hundreds of cells, then the apparent limitation vanishes.
Other arguments may be a column label, a mathematical constant, or a value unique to that function.
Depending on the function, arguments may have to be entered with straight quotation marks. However, this requirement is not consistent. Otherwise similar formulas may differ only in this requirement, and no simple rule tells you which is which. You simply have to know or check the requirements in the online help.
The only exception to these structural rules are basic arithmetical functions entered with symbols. For example, instead of entering =SUM(2;3), you can enter =2+3.