LibreOffice Tips and Tricks
From Free Knowledge Base- The DUCK Project: information for everyone
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. Although the ISO 8601 date format of YYYY-MM-DD is the most logical, it is not what Americans are accustomed to.