You can use the following formulas:
For 2020 use in cell D2
You will get a number like 4.475757576. Format the cell as Duration to get the hours (if not interested leave it as is).
Following that, you can use the following formula in cell D3
=INT(D2)&"D "& ...
This is an old question, but I want to share my way of solving it (In case someone end here without answer).
Format> Number> More Formats> Custom number format
In there you write the following:
Remember to write exactly this format, even if the hours, minutes or seconds are double ceros (00) so an ...
(following OP's comment)
...to include a custom start and end date which I know I didn't ask for based on your reply
Please use the following formula:
More about SEQUENCE
Maybe: The From date could be hiding a time element that is used in the calculation, but is not included in the display. For example, if you change your from date to be 2020-3-5 02:18 then it will change the calculated bill to €47.23