Do you want to find them or remove them

to find them

=IF(COUNTIF($A$1:$A$20,A1)1,"Duplicate","")

in a help column copy down and it will tag each number/value that occur
more than once. If you only want to tag from the second occurrence

=IF(COUNTIF($A$1:$A1,A1)1,"Duplicate","")

both formulas should be copied down

if you just want to remove any duplicates and get a unique number column use
dataadvanced filter and unique records only

Regards,

Peo Sjoblom


"Johnny the hat" wrote:

Is there a formula to find duplicate numbers in columns in excel