Question: How do I get the largest and smallest unique and duplicate value?

Answer:

min-max-unique-duplicate-value-in-excel

Max duplicate value, formula in C22:

=MAX(IF(COUNTIF(List, List)>1, List, )) + CTRL + SHIFT + ENTER

Min duplicate value, formula in C24:

=MIN(IF(COUNTIF(List, List)>1, List, "")) + CTRL + SHIFT + ENTER

Max unique value, formula in C26:

=MAX(IF(COUNTIF(List, List)=1, List, )) + CTRL + SHIFT + ENTER

Min unique value, formula in C28:

=MIN(IF(COUNTIF(List, List)=1, List, ""))+ CTRL + SHIFT + ENTER

Named ranges
List (A2:A20)
What is named ranges?

How to implement array formula to your workbook
Change named range.

Download excel example file.
Min and max unique and duplicate values.xls
(Excel 97-2003 Workbook *.xls)

Functions in this article:

IF(logical_test;[value_if:true];[value_if_false])
Checks whether a condition is met, and returns one value if TRUE, and another value if FALSE

MIN(number1,[number2])
Returns the smallest number in a set of values. Ignores logical values and text

COUNTIF(range,criteria)
Counts the number of cells within a range that meet the given condition

MAX(number1,[number2],)
Returns the largest value in a set of values. Ignores logical values and text.