Let a, b and S be 3 real variables. The last one being the result of the multiplication of the two first.

We would like to create an event between a and S and between b and S so that when the field a or b is validated, S is updated.

Let take the example of the creation of the event between a and S (the one between b and S is the same) :

Select the fields of a and S by taking care that the last selected field is a.

Select the add events icon

The add events box opens, write the a*b expression.

Validate by     OK    .