Conditional Formatting : - Select your data range. - Go to "Home" > "Conditional Formatting" > "Highlight Cell Rules" > "Duplicate Values". 2. Formula : - Use COUNTIF or COUNTIFS to check for duplicates. - Example formula: =COUNTIF(A:A, A1)>1 (assuming your data is in column A). 3. Remove Duplicates : - Select your data range. - Go to "Data" > "Remove Duplicates" and select the columns where you want to find duplicates. 4. Pivottable : - Create a PivotTable with your data. - Put the column you suspect is duplicate in both "Rows" and "Values". - Excel will count occurrences, highlighting any values with a count greater than 1 as duplicates.