I would be most grateful if someone could offer me some help.

I need to count the number of unique values within a column range. The range
is between B2:B65536. Each value consists of a series of alpha and numerical
characters and there are blank cells within the range.

There will be around 30,000 plus entries.

I have used various formulas, but due to the vast number of rows of data
they crash.

An example of one of the formulas I used is below:

=SUMPRODUCT((1/COUNTIF(A1:A5,A1:A5&"")))

I am desperate for an answer but am confused as to how to do this? Any help
or assistance would be very much greatly appreciated.