I am currently working on setting up a call cost register for my workplace.

I have set up formulae in columns D, E and I, beginning at row 4 (so, D4, E4
and I4) to calculate various figures; however, I need a macro that will
either:

1. Autofill those formulae down the column regardless of whether the
previous row was fully completed (column I is the final column of the
register and does not always require an entry); or,

2. Allow those 3 formulae to function within every following cell of those
columns (for instance, the formula is D4 will function in ever cell from D4
to D65536)

I have very limited VBA knowledge, so if anyone could help it would be
greatly appreciated.