Many thanks for all your help - I forgot to say that some of the cells within
the column are blank. Do I need to alter the formula in anyway? I suspect
this maybe why I am having problems.

"Sean Timmons" wrote:

Not sure why it would crash, but you do have an extra ) at the end. It worked
fine for me...

"SiH23" wrote:

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. Each
value consists of a series of alpha and numberical characters.

I have used the formula below but it keeps crashing my spreadsheet:

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

Any help or advice would be greatly appreciated.