Formula can be created using number , date and time column types of columns. Other columns can't be used in the formula.

Only formula type of columns can have a formula.

Press the column header (or column name) of a formula column.

Press the formula box

Enter the expression using numbers in the calculator keyboard. Press select column to add a column. Only date, time , number and formula type of columns can be added.

Press Ok button to set the formula.

Time and date columns can be used to compute time duration in hours or days. This feature is available since version 53.