human
How to highlight duplicates on Google Sheets?
assistant
Highlight Duplicates on Google Sheets on PC or Mac
1. Open Google Sheets.
2. Click a spreadsheet.
3. Select a cell range.
4. Click the Format tab.
5. Select Conditional formatting.
6. Select Custom formula is on the "Format cells if" menu.
7. Type "=COUNTIF(A:A,A2)>1" into the formula box.
8. Click Done.