Formulas are involved in most parts of the mathematical curriculum in upper secondary education and in everyday mathematics classrooms, but research shows that students have difficulties using formulas adequately. When students are presented with a task, the task activates a conceptual frame in the students, making them perceive formulas in a specific way, thereby affecting their mathematical behaviour. In this paper, building ideal types of patterns of mathematical behaviours is used to conceptualise 'view on formula' specified by several specific views. The concept of 'view on formula' is applied in an analysis of a classroom episode pointing to reasons for the difficulties students have with handling formulas. When views are either missing or not used in a flexible way this can lead to an unsuccessful handling of formulas. Also, students' views on formula may indicate what knowledge is missing for solving a task involving formulas. Taken together, this points to the importance of paying attention to views on formulas in the everyday mathematics classroom.