V-look up fuction

I'm having trouble using the V-look up function. I have two excel documents open, I need to find if any of the values in the first excel are ALSO in the second excel file. Can anyone please help me step by step? Your advise is much appreciated
Thanks

I suspect that you might want to use MATCH() rather than VLOOKUP()
=MATCH(A1,[Book2]Sheet1!$A$1:$A$30,0)
will check the cells A1 to A30 of Sheet1 in the workbook Book2 to see if any have the same value as cell A1 on the current sheet in the current workbook.

It will return the position, within the range, of the first cell that matches or it will return #N/A if there are no matches.

You can then use ISNUMBER(MATCH(....)) to give a TRUE of FALSE result depending on if there are any entries the same in the two workbooks.

Hope this helps.

Mark.