i can't find a formula that verifies if something repeats on a column

Question

I'm doing a project in googlesheets and i need to use a formula that verifies if an input on a segment repeats in other segments on the same column.

Thanks in advance.

Answer 1

If you wanted to list which values were repeated, you could do it as single formula using:

=filter(unique(A:A),countif(A:A,unique(A:A))>1)

If you just wanted to know if there were any repeats anywhere, then it would just be

=counta(A:A)<>countunique(A:A)

Or if you wanted to flag up each row to show whether it was repeated or not:

=ArrayFormula(if(A:A<>"",countif(A:A,A:A)>1,))

Answer 2

Assuming your inputs are A1:A8, starting with A1:

=IF(COUNTIF($A$1:$A$8, A1) = 1, "UNIQUE", "REPEATS")

Result