Some of the most fundamental of the Excel functions (notably IF and SUM) have so many potential uses that it is not possible to list them all. Generally, they will be used in specific contexts where the need for them is self-evident, and without needing to make any particular comments on why or how they are used. Nevertheless, on occasion it is useful to point out some contexts or structures in which their use is quite frequent.
This chapter shows some such examples in a model which has multiple time periods (i.e. a revenue forecast over 5 years, similar to the models built earlier):
By way of explanation: