How to highlight duplicates in google sheets?

I dont know much about how Google Sheets works but I did find this which seems to have some successful instructions: http://stackoverflow.com/questions/2...le-spreadsheet

If you scroll down the page, there is a response from CommonRaven that has 14 votes. That solution worked for my test. I hesitate to copy paste the solution as I do not know the rules for such a move on this forums and I do not want to run afoul of the forum or the moderators. It is the 3rd high level response to the problem, however.