I have a bunch of data in a spreadsheet where the left-most column represents a date in the format DD-MM. Here's an example for column A:
I took that date and in, LibreOffice Calc, created another column to add the year and make it DD-MM-YYYY format in column B (the data span multiple years).
Then I formatted the cells in column B as Date, with the appropriate (user-defined) DD-MM-YYYY format. Calc seemed to recognize it as a date and I thought all was good. But when I tried to do a "days between" calculation, e.g.
all I got me was "#VALUE!". Nothing I did to change the format seemed to make the calculation work. I tried the same in Google Spreadsheets and got the same result.
How can I take date-formatted data then do a calculation on it?