highlight a cell if its value is in another row

[vg05]

hello, i'm looking for some help in conditional formatting. I am trying to highlight 1 cell (K3) if the value of K3 - which will change - is found anywhere in column A.

the purpose of this is to check for duplicates in a very long list of data without having to scroll down. I would type a number in K3, and if that number exists in column A, K3 would light up.

Thanks

[AliGW]

Your rule for K3:

=ISNUMBER(MATCH(K3,A:A,0))

[vg05]

thank you! worked like a charm

[AliGW]

You're welcome.

[NebulousVoidica]

Hi,

This got me 90% of the way! If I could piggyback on this thread..?

I keep a running list of vendors on my "Starts" (table name "VendorList") sheet. I'd like to Highlight any cells is my "Data" sheet that contain any vendors in my list on Starts $I3:I$I32. Can I manipulate the above formula?