Counting the number of unique entries

- We're looking at a worksheet called HR List,…and I'm focusing on column C.…I'm a bit curious.…I want to know how many different Departments we have.…I just don't have a list anywhere.…How many different ones are there?…There ought to be a way to somehow count…how many different Departments there are here.…Now, if we sort the data,…we'll pull them together by clusters.…But that doesn't really count them.…There is a way to count the number…of unique entries in a range.…And one of these days I expect to see…a function in Excel called unique.…But it's not there yet.…The way to do this is unusual.…

And it involves a formula called an array formula.…I'm going to zoom in on this a bit using shift control.…I'm using a mouse with a wheel, so I'll use the wheel.…If it were a track pad,…I'd be using two fingers on the track pad…or a single finger on the mouse,…again, holding down control and shift.…I'm going to Insert a new row above row 1…and create a formula in cell C 1.…Now, ahead of time I need to know…how many entries are in this column.…