Short bio: Computer Scientist, FOSS supporter (read more)
Tux Machines (TM)-specific
Once you are comfortable with inputting functions and formulas, the next step is to learn how to automate the processes. Calc includes over half a dozen tools to help you manipulate functions and formulas, ranging from features for copying and reusing data to creating subtotals automatically to ones for varying information to help you find the answers that you need. These tools are divided between the Tools and Data menus, according to no apparent logic.
If you are a newcomer to spreadsheets, these tools can be overwhelming at first. However, they become simpler if you remember that they all depend on input from either a cell or a range of cells that contain the data with which you are working. You can always enter the cells or range manually, but in many cases, you can also use the Shrink/Maximize icon beside a field to change temporarily the size of the tool's window while you select the cells with the mouse. Sometimes, you may have to experiment with which data goes into one field, but, once you have found out, the rest is simply setting a selection of options, many of which can be ignored in any given case. Just keep the basic purpose of each tool in mind, and you should have little trouble with Calc's function tools.
Copying and reusing data
Data -> Consolidate provides a graphical interface for copying data from one range of cells to another, then running one of a dozen functions on the data. Most of the available functions are statistical (such as AVERAGE, MIN, MAX, STDEV0, and the tool is most useful when you are working with the same data over and over.