When trying to calculate expected costs by having a formula field with this value: {Estimated time} /60*65 (which is the hourly rate), the answer shown is in hours and minutes. There is no option to choose a different unit, euros (€) having my preference but just a plain number (integer) is also okay.
Adding a new column with the hourly rate will fix this, but it forces me to fill it in for every task. The hourly rate is constant for the project.