LibreOffice Tips and Tricks
Calc: Date Format and Partial Entry
If you highlight the column and press CNTL-1 a dialog with options appears. Make sure the language is set to English.
When using Excel, a partial date entry such as MM-DD ie: 1-25 will automatically result in conversion to the configured format, for example MM/DD/YYYY or 1/25/2018. This does not occur by default in Calc because Calc doesn't recognize the dash as a date separator. This was not a problem in older versions (3.5x and earlier). Here's the fix: On the top menu click ( Tools -> Options -> Language Settings -> Languages ) and add two additional patterns to the field labeled "Date acceptance patterns:" so that the full contents of the field are as follows:
M/D/Y;M/D;M-D-Y;M-D
Apparently some smug little programmer decided that it was just plain wrong for folks to be using dashes in their date, so he removed it from the standard patterns. There have been multiple complaints and bug reports so it will likely be corrected in future versions.
Tip: CTRL + ; will automatically enter the current date in the active cell.