excel autofilter arrow custom query

R

ROB SPEKSNIJDER

hello and thanks for any future help you can give me.
i am making a spreadsheet to record data for statistical purposes. m
problem is; that i have one column of numbers, that i want to hav
saved on this spreadsheet when i open it, and then another column o
numbers, that i will put on this spreadsheet after i have opened it
some of the numbers in the columns may well be duplications, copies
and so i would like to set-up a third column, which shows th
duplicated numbers. i have put on an autofilter, and using the arrow
selected custom thinking that i could put in a formula for this thir
column that would highlight all of the duplicates. this has not worke
so i am now wondering if someone could help me with how the thir
column could extract the necessary data from the first and secon
columns and present the duplicates to me in this third column. like i
say, all help greatly appreciated.
regards
ro
 
R

R Douglas

Dear Rob:

If the first column of numbers is sorted in ascending order then you can use
the LOOKUP() function to find duplicates. For example, if the first column
of numbers is in A1:A10 and the second column of numbers is in B1:B10, put
in cell C1 the following formula,
=IF(LOOKUP(A$1:A$10, B1)=B1, B1, "")
Copy this formula to C2:C10. It will show only the duplicates that are in
both column A and column B.

Regards,
R. Douglas
 
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