Check the number of unique cells in a range

Question

I have an excel sheet.

Under column E, I have 425 cells with data. I want to check if the same data (i.e. text inside the cell) is repeated anywhere else in any of the remaining 424 cells under column E. How do I do this?

For example, in E54 I have
Hello Jack

How would I check this value to see if it was in any other of these cells?

Answer 1

You could use

=SUMPRODUCT(1/COUNTIF(E1:E425,E1:E425))

to count the number of unique cells in E1:425

An answer of 425 means all the values are unique.
An answer of 421 means 4 values are duplicates of other value(s)