For people living in countries where the decimal comma is used.
Currently, the Formulas question does not allow students to use the decimal comma in their answers; only the decimal point is accepted. Supporting the decimal comma is one of the priority features to be implemented in the Formulas question code. In the meantime, you can use a JavaScript snippet as illustrated below. More information is available at https://dynamiccourseware.org/course/view.php?id=22#sectionid-1579-title.