How to Find and Remove Duplicates in Google Sheets

=countif(E1:E,E1)>1

I hate Macs and I hate Google products. Trying to be different and utterly worthless. This didn't even work.

thanks bro

=countif(A1:A,A1)>1

This is a pain and I bailed 30 seconds into the video. The label should be "Weird and Obscure Way to Remove Duplicates"

Could you set that the last cell of the condition will become green too? like B9 and B16 and C16 and D14 etc? I mean, if they are still white, and they are at like row 1000, I can't tell if it's duplicated unless I scroll back to the previous rows looking for green. In some cases, I prefer the one who use the spreadsheet is noticed that he/she is entering a duplicated data.