How do I identify duplicated numbers in a large range of cells

[gillman54]

I have a large range (column) of cells (3567) which contain Alpha numerical
i.d codes, I want to indentify cells where i.d codes are duplicated

 

[Max]

Assume source data in A2 down
Put in B2: =IF(COUNTIF(A$2:A2,A2)>1,"dup","")
Copy B2 down to the last row of data in col A to flag duplicates as "dup".
You can apply autofilter on col B, choose: dup to retrieve all at one go
--
Max
Singapore
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xdemechanik

 

[Jack Gopher]

Have a look at the video named "Using vlookup to Match Lists" over here:
http://www.free-training-tutorial.com/function-vlookup.html


Or the video named: "Finding duplicate values or unique values with
conditional formatting" over here:
http://www.free-training-tutorial.com/conditional-formatting.html