Since version 1.43 and onwards, calculations are now written using our own expression language KEX. A calculation is at the core a script written in the KEX language but there is an graphical user interface (GUI) that can be used to build most calculations. It's always possible to go from the GUI to the script editor but not always the other way around since scripts are more flexible in structure and also support a few features not yet available in the GUI. When creating a calculation, you're prompted to choose calculation type.
Typically, you'll find advanced settings and more details in the side panels to the right in the calculation editor (this design pattern is also used in other parts of the admin interface such as editors for valuetypes and dimensions.