On numerous occasions we have used the preset conditional format for
highlighting duplicate or unique values. However, we now have come across
the need to highlight duplicate or unique values only if those values meet
certain other criteria also. Such a task will lwill likely require a
formula, but we are not sure how the Excel so effectively compares values in
a large range to identify duplicate or unique values . If we knew how Excel
was so efficiently performing these comparisons, we might could incorporate
the functions for finding duplicate or unique values and then add additional
tests in the same formula.

Any ideas on how Excel can so quickly compare all the values in a large
range to see if any of them are duplicates or uniques? Is there a function
that can simulate that operation, yet also be combined with other functions
in a larger formula?

We would also like to, as an option, be able to find duplicate or unique
values without regard to capitalization or for perhaps even for partial
matches. Is this possible?

Thank you for any help.