find duplicates in list

[Ann]

i have a single column of data. how do i highlight the duplicates in the
list. i've tried conditional formatting and can't get the formula right.
some rows might be duplicated 4 times and others just 2. tia

 

[joel]

If you start in row 2

In cell A2
Or(A2=A1,A2=A3)

 

[joel]

If the duplicates aen't in adjacent rows

=COUNTIF(I:I,I1)>1

 

[ryguy7272]

Try these:
=IF(COUNTIF($A$1:$A$55,$A1)>1,$A1,"")

=IF(AND(COUNTIF($A$1:$A$55,A2)>1,COUNTIF($L$1:L1,$A2)<1),$A2,"")


Note: these functions count uniques
=SUMPRODUCT(1/COUNTIF(A1:A55,A1:A55))
=SUM(--(FREQUENCY(A1:A55,A1:A55)>0))
=COUNT(1/FREQUENCY(A1:A55,A1:A55))

HTH,
Ryan---