checking other pages and workbooks for repeating numbers?
 

How do I check to see if a number has already been used in another workbook
or on another page? Such as (j11=7pfo1by) is billable area and (k11=54635) is
billable item this can only be billed once and I would like for excel to
check the entire weekly workbook and other workbooks for this specific set of
numbers. If I type them in it would tell me that set of numbers have already
been used. Both sets of numbers must be the same I could have the same item
number in another billiable area but I will not have the same item and aera
twice.