If the 'active cell' was A15 then that formula would be COUNTIF(A$1:A$15 A15)>1. It is important to get the 'active cell' correct. Go to Format ► Conditional Formatting and set up a rule as a formula using COUNTIF(A$1:A$15 A1)>1. Select the column of numbers and note the 'active cell' (A1 in the sample image below). Error or any you defined in advance)Ĭheck that your cell range is A1:A1048576 (You may want to reduce the 1048576 to any reasonable number you assume will be the maximum to ever be used) Select the menu: Format -> Conditional -> Condition.Ĭondition 1: Cell value is and select duplicate from the dropdownĪpply Style: Select your cell style (e.g. Select column A by clicking on the header character A (the top of the column) In LibreOffice Calc 6.0.7.3 this can be done by following these steps (from this link): If the column is not the major order (ie 2nd or later in the sort criteria) then the 'uniqueness' is effectively 'reset' each time sorting starts over for this column. In a sorted column, the first occurrence of a value will be considered 'unique' in that it hasn't occurred yet, and then all of the duplicates which follow immediately afterward are flagged (I usually use a light grey for the font color). If you want to format any value in a cell that is a duplicate of the one immediately above it, select the entire column and use the following formula in Conditional Formatting (INDIRECT(CELL('address'))=OFFSET(INDIRECT(CELL('address')) -1 0)) Not exactly the solution to this specific question, but I find the following comes in very handy when you have the column in question sorted, especially when you are sorting by multiple columns:

Openoffice calc highlight duplicates