# User functions

Wiris Quizzes Studio uses symbolic notation so we can work with variables and symbols. This is extremely useful but then `f(x)`

is understood as a multiplication . If we want that to be interpreted as a function evaluated at a point , we need to declare it as a *User function* in *Validation > General > Options for general*.

Let us see a question example

This is the well-known statement of the Fibonacci sequence. We ask for two answers: the relation and a particular term of the series. Thus, the *Correct answer* tab will look like

Note that since is marked as a *User function*, it is shown in blue, as any other elemental function ().

This feature is also useful when considering composition of functions questions.