A week and two days
Give a row a rate per day and a rate per week. Nine days is then not nine days at the day rate — it is a week and two days, whichever combination comes to least, and never a fortnight rounded up.
The bill shows its working, one line each, so nobody has to trust a total. A price written with a comma is read as a decimal mark, which matters most on a number that gets multiplied by ten.


