How to negate 'isblank' function

I want to do "is not blank" in a custom formula. There is a isblank() function but I can find neither an isnotblank() function nor a way to say not, such as ! or ==False.

How can I say is not blank?

I suggest:

=not(isblank(A1))  

which returns TRUE if A1 is populated and FALSE otherwise. Which compares with:

=isblank(A1)  

which returns TRUE if A1 is empty and otherwise FALSE.

The solution is isblank(cell)=false

If you're trying to just count how many of your cells in a range are not blank try this:

=COUNTA(range)

Example: (assume that it starts from A1 downwards):

---------    
Something 
---------
Something
---------

---------
Something
---------

---------
Something
---------

=COUNTA(A1:A6) returns 4 since there are two blank cells in there.