I have data in column A. The last row filled is row number 20
I have a formula in cell C1.

I want to detect the last filled row in column A (in this example, it
is row no.20) Once the detection is over, the vba should drag formula
in C1 till C20.

The next day I will paste some more data in column A. After running the
same macro, again the same thing should happen. Detect the NEW last row
number and drag formula from C1 till CXX (XX=NEW last row)

Can anybody help?