A friend recently asked me, “How do I condition format duplicates for Long Numbers formatted as text?”
I thought…that is easy!
Just go to condition formatting and select the in-built rule of highlighting duplicate rules.
Hardly did I know Excel has a 15-digit limit to precision!
The only alternative is to use the below formula
=SUMPRODUCT ( (range=criteria)+0 )>1
See the explanation in the video below