If your formulas are simple and straightforward you can get away with re-using bits and pieces in multiple formulas. But you notice that things can get confusing quite fast! We have created Variables to make sure your head won't explode while building a calculator with complex calculations.
Variables act in the same way as Formulas. There is one important difference! A formula is a form element. So formulas are displayed in your calculation form. Variables are only visible if they are used in a formula.
You can create a variable by expanding the formula editor and clicking on the "Add variable" button. Once you have created the variable, you can use it in any function. You can even nest variables, so you can use variables in other variables. Be careful though about the order in which the variables are defined. Variables that contain a nested variable that is listed below the original variable, will result in an error.